sonometro - larson davis dsp81

DSP80 Series

Reference Manual

Larson Davis Inc.1681 West 820 North

Provo, UT 84601-1341Phone: (801) 375-0177FAX: (801) 375-0182www.larsondavis.com

I80.01 Rev. A

DSP80 Series Reference Manual

ii

Copyright

Copyright 2000 by Larson Davis, Incorporated. This manual is copyrighted, with all rights reserved.The manual may not be copied in whole or in part for any use without prior written consent of LarsonDavis Inc.

Disclaimer

The following paragraph does not apply in any state or country where such statements are not agree-able with local law:

Even though Larson Davis, Inc. has reviewed its documentation, Larson Davis Incorporated makes nowarranty or representation, either expressed or implied, with respect to this software and documenta-tion, its quality, performance, merchantability, or fitness for a particular purpose. This documentationis subject to change without notice, and should not be construed as a commitment or representation byLarson•Davis Inc.

This publication may contain inaccuracies or typographical errors. Larson Davis Inc. will periodicallyupdate the material for inclusion in new editions. Changes and improvements to the informationdescribed in this manual may be made at any time.

Warranty

Larson Davis warrants this product to be free from defects in material and workmanship for two yearsfrom the date of the original purchase. During the two year warranty period, Larson Davis will repairor, at its option, replace any defective component(s) without charge for parts or labor if the unit isreturned, freight prepaid, to an authorized service center. The product will be returned freight prepaid.

Product defects caused by misuse, accidents, or user modification are not covered by this warranty.The warranties described above are exclusive and in lieu of all other warranties whether statutory,express or implied including, but not limited to, any implied warranty of merchantability or fitness fora particular purpose and all waranties arising from the course of dealing of usage or trade. The buyer’ssole and exclusive remedy is for repair or replacement of non-conforming product or part thereof, orrefund of the purchase price, but in no event shall Larson Davis ( its contractors or suppliers of anyspecial indirect, incidental, or consequential damages) whether the claims are based in contract, in tort(including negligence), or otherwise with respect to or arising out of the product furnished hereunder.Representation and warranties made by any person, including its authorized dealers, representatives,and employees of Larson Davis which alter or are in addition to the terms of this warranty shall not bebinding upon Larson Davis unless in writing and signed by one of its officers.

Larson Davis is an equal opportunity employer and does not discriminate on the basis of race, color,religion, gender, national origin, disability or veteran status.

Please examine your instrument and record the following information below. You may be asked togive this information in any future communications you have with Larson Davis, Inc.


iii

Record of Serial Number and Purchase Date

Pre-amp Serial #: ________________________

DSP8X Serial #: _______________________ Purchase Date: _________________________

Microphone Model #: ___________________ Microphone Serial #: _____________________

Pre-amp Model #: ____________________


iv

Table of Contents

Chapter 1 Introduction 1-1About This Manual .................................................................................................1-1

About This Chapter.................................................................................................1-2

Formatting Conventions .........................................................................................1-2

Features...................................................................................................................1-3

DSP80 Series Instrument Components ..............................................................1-5

System Diagram.................................................................................................1-6

Getting Started ........................................................................................................1-7

Unpacking and Inspection..................................................................................1-8

Accessories and Optional Equipment ................................................................1-8

Connecting Internal or External Power..............................................................1-9

Environmental Considerations.........................................................................1-10

Data Retention..................................................................................................1-11

Chapter 2 Instrument Keypads and Calibration 2-1Understanding the DSP80 Keypad .........................................................................2-2

Understanding the DSP81 Keypad .........................................................................2-4



Understanding the DSP80 Series Screen ..............................................................2-10

Turning On the DSP80 Series Sound Level Meter...............................................2-11

Calibrating the DSP80 Series Sound Meter..........................................................2-13

Chapter 3 Simple Tutorial 3-1Instrument - Functionality Matrix...........................................................................3-2

Functionality - Instrument Matrix...........................................................................3-3

Selecting a Frequency Weighting ...........................................................................3-4

Selecting Exponential Time Weighting..................................................................3-4

Checking the Battery Voltage.................................................................................3-5

Performing a Measurement and Reading the Data .................................................3-6

Viewing Leq, LpkC and LpkU......................................................................................................... 3-7

Selecting Octave Filters (for DSP81 and DSP83 Meters) ......................................3-7

Pausing and Resuming a Measurement ..................................................................3-8

Stopping a Measurement ........................................................................................3-9

Turning Off the DSP80 Series Meter .....................................................................3-9

Chapter 4 Reference 4-1Introduction.............................................................................................................4-2


vi

(Battery Key)..............................................................................................4-4

, , (Calibrate, Up, and Down Arrow Keys) ......................................4-4

(Fast Exponential Time Weighting Key) ...................................................4-5

(Impulse).......................................................................................................4-6

(Integrating Sound Level Key) .....................................................................4-6

(Off Key).......................................................................................................4-8

(On/Run Key) ...............................................................................................4-8

or (Octave Filters) .............................................................................4-10

(Reset Key) ............................................................................................4-11

(Slow Exponential Time Weighting Key) ..............................................4-11

(Stop Key) ................................................................................................4-12

or (Frequency Weighting Key)......................................................4-12

Chapter 5 Remote Interface 5-1Remote Commands.................................................................................................5-2

Appendix A Specifications A-1General...................................................................................................................A-2

Type .......................................................................................................................A-3

Reference Direction ...............................................................................................A-3

Primary Indicator Range........................................................................................A-4

Reference Level .....................................................................................................A-5

Frequency Weightings ...........................................................................................A-5

Detector Time Weightings.....................................................................................A-5

Effects of Temperature ..........................................................................................A-5

Effects of Humidity ...............................................................................................A-5

Limits of Temperature and Humidity ....................................................................A-6

Microphone Extension Cables ...............................................................................A-6

Calibration Procedure ............................................................................................A-6

Positioning of Instrument & Observer for Measurements.....................................A-6

Limitations on Output Electrical Impedance .........................................................A-7

Reference Frequency .............................................................................................A-7

Warm-up Time.......................................................................................................A-7

Microphone Electrical Impedance .........................................................................A-7

EMC Compliance Testing .....................................................................................A-8

DSP80, DSP81, DSP82, DSP83 .......................................................................A-8

Appendix B Instrument and Microphone Response Curves for the DSP80, 81, 82, & 83 B-1


vii

Log Linearity, Differential Linearity and Range Data......................................B-3

Weighted Peak Linearity...................................................................................B-4

Certificate of A-Weight Electrical Conformance .............................................B-5

Certificate of B-Weight Electrical Conformance..............................................B-6

Certificate of C-Weight Electrical Conformance..............................................B-7

Results of Crest Factor Tests ............................................................................B-8

Results of Burst Tests .......................................................................................B-9

Results of Detector Tests ................................................................................B-10

Relative SPL Awt Slow vs. Humidity at 40° C ..............................................B-11

Relative SPL Awt Slow vs. Temp at 36% RH................................................B-12

Relative SPL Awt Slow vs. Humidity Endurance at 40° C and 90% RH ......B-13

Certificate of 31.5 Hz Octave Filter Shape .....................................................B-14

Certificate of 63 Hz Octave Filter Shape........................................................B-15

Certificate of 125 Hz Octave Filter Shape ......................................................B-16



Certificate of 1000 Hz Octave Filter Shape....................................................B-19

Certificate of 2 kHz Octave Filter Shape........................................................B-20

Certificate of 4 kHz Octave Filter Shape ........................................................B-21

Certificate of 8 kHz Octave Filter Shape ........................................................B-22

DSP80 Free-field response @ 0°with PRM80 preamp & 2551 microphone .B-23

DSP80 Free-field response @ 90°with PRM828 preamp, 2551 microphone and random incident corrector ...............................................................................B-24

DSP80 Random response with PRM828 preamp, 2551 microphone and random incident corrector ............................................................................................B-25

DSP80 Free-field response @ 0°with PRM828 preamp & 2551 microphoneB-26

DSP80 Random response with PRM828 preamp and 2551 microphone .......B-27

DSP80 response with PRM828 preamp and 2551 microphone @ 1 kHz.......B-28




DSP80 response with PRM828 preamp and 2551 microphone @ 12.5 kHz..B-32

Appendix C Glossary C-1Allowed Exposure Time (Ti) .......................................................................C-1

Average Sound Level (Lavg) .......................................................................C-1

Community Noise Equivalent Level (CNEL, Lden)....................................C-2

Criterion Duration (Tc) ................................................................................C-2

Criterion Sound Exposure (CSE) .................................................................C-2


viii

Criterion Sound Level (Lc) ..........................................................................C-2

Daily Personal Noise Exposure (LEP,d) ......................................................C-3

Day-Night Average Sound Level (DNL, Ldn).............................................C-3

Decibel (dB) .................................................................................................C-3

Department of Defense Level (LDOD)........................................................C-6

Dose..............................................................................................................C-6

Detector ........................................................................................................C-6

Eight Hour Time-Weighted Average Sound Level (L TWA(8)) .................C-7

Energy Equivalent Sound Level (Leq).........................................................C-7

Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k) ..........C-7

Far Field .......................................................................................................C-8

Free Field......................................................................................................C-8

Frequency (Hz, rad/sec) ...............................................................................C-8

Frequency Band Pass Filter..........................................................................C-8

Frequency Filter - Weighted ........................................................................C-9

Leq..............................................................................................................C-10

Level (dB) ..................................................................................................C-11

Measurement Duration (T).........................................................................C-11

Microphone Guidelines ..............................................................................C-11

Near Field...................................................................................................C-13

Noise...........................................................................................................C-14

Noise Dose (D)...........................................................................................C-14

Noise Exposure ..........................................................................................C-15

OSHA Level (LOSHA)..............................................................................C-15

Preamplifier ................................................................................................C-15

Projected Noise Dose .................................................................................C-15

Single Event Noise Exposure Level (SENEL, LAX) ................................C-15

Sound..........................................................................................................C-15

Sound Exposure (SE) .................................................................................C-16

Sound Exposure Level (SEL, LET) ...........................................................C-16

Sound Pressure ...........................................................................................C-16

Sound Pressure Level (SPL, Lp) ................................................................C-17

Sound Power(W) ........................................................................................C-19

Sound Power Level (PWL, Lw).................................................................C-19

Sound Speed, (c,) .......................................................................................C-19

Spectrum (Frequency Spectrum)................................................................C-19

Threshold Sound Level (Lt) .......................................................................C-20

Time Weighted Average Sound Level (TWA, LTWA(TC)).....................C-20


ix

Time Weighting..........................................................................................C-20

Vibration.....................................................................................................C-20

Wavelength (l)............................................................................................C-20

Wavenumber (k).........................................................................................C-21


x

6/11/01 Introduction 1-1

C H A P T E R

1 Introduction

Welcome to the Larson Davis DSP80 series sound levelmeters. These affordable, lightweight sound level meters usedigital signal processing (DSP) electronics for outstandingdynamic range. The DSP80 series instruments measuresound with the ease of operation of a “point and shoot”sound level meter. Many users are able to deduce the opera-tion of each of the DSP80 series instruments almost entirelyby glancing at its keypad. However, we invite you to readthis short manual to get the most out of your new LarsonDavis sound level meter.

About This Manual

This manual has 4 chapters and 3 appendices covering thefollowing topics:

• Chapter 1 - Introduction: overview of this user manualand the DSP80 series instruments functions and mea-surement capabilities

• Chapter 2 - Instrument Keypads and Calibration: anexplanation of the DSP80 series keypads and screens,along with instructions for turning on and calibrating theDSP80 series instruments.

• Chapter 3 - Simple Tutorial: Instructions for makingsimple measurements on the DSP80 series instruments.

• Chapter 4 - Reference: description of each key alongwith its function and displays.

• Chapter 5 - Remote Interface: explanation of RS-232commands and syntax

1-2 DSP80 Series Reference Manual 6/11/01

• Appendix A - Specifications: listing of acoustic, elec-tronic, environmental, and physical characteristics of theDSP80 series instruments

• Appendix B - Instrument and Microphone ResponseCurves: illustrations of continuous frequency response,random base correction, and directional response curves

• Appendix C- Glossary: definitions of key terms and con-cepts used in this manual

About This Chapter

Specifically, this introductory chapter covers the followingtopics:

• Formatting Conventions: explanation of the fonts andother formatting conventions used in this manual

• Features: overview of the DSP80’s keypad, functionsand measurement capabilities

• Getting Started: instructions for unpacking, inspecting,and initially assembling the DSP80 series sound levelmeter

Formatting Conventions

This manual uses the following formatting conventions:

Functions accessed by pressing a key on the DSP80 serieskeypads are shown with an icon, for example:

In step-by-step directions, the process (what you do) isshown in the right column, and the rationale (why you do it)

Press and then press .


with other cautions and comments are shown in the left col-umn. For example:

Especially important information is shown in italics, forexample:

This affordable, lightweight sound level meter usesdigital signal processing (DSP) electronics for out-standing dynamic range and flexible filtering,while maintaining full Type 1 accuracy.

Features

The Larson Davis Model DSP80 series instruments meet therequirements of the American National Standards Institute(ANSI) S1.4-1983 and S1.11-1986, International Electro-technical Commission (IEC) 651-1979, and 804-1985 stan-dards for Type 1 accuracy, and offer the following features:

• Dynamic range of more than 100 dB

• A, B and C frequency weightings

Step 3 After approximately 1 second, the nextdisplay automatically appears:

Step 4 After approximately 1 second, the fourthdisplay automatically appears:

This third display shows the revisionnumber of the firmware (e.g., 2.00)which is uniquely assigned to yourmicrophone. This message appearsfor only 1 to 2 seconds.

rev # 2.00


• FAST, SLOW, and impulse exponential time weighting

• C-weighted and unweighted PEAK detectors

• Leq integrated level (duration ranging from 1 second to99 hours, manually controlled)

• Maximum rms (Fast, Slow, and impulse) level since lastreset

• Quartz crystal controlled integration time display

• Calibration from front panel (using an appropriate cali-bration source)

• Easy one step reset of measurement

• Digital battery voltage indication in tenths of volts

• Standard 9V internal alkaline battery life of more than 6hours (or external power using LD cable CBL063 forlonger measurements)

• Addressable RS-232 communication at 9600 BAUD rate(8 bit, 1 stop, no parity)

• Field replaceable 10.6mm (3/8 in.) diameter electretmicrophone (equalization curve must be reloaded)

• Large, two line, 32 character, high contrast LCD display

• Small [20.5cm x 7.5cm x 2.5cm (8” x 3” x 1”) H x W xD] and lightweight (252 g = 7 oz.)

• Rugged ABS case

• EMI and EMC protection to CE requirement

• Durable membrane keypad

• Two-year warranty (see warranty statement on the copy-right page at the front of this manual)

• IEC free-field response (or ANSI random response whenordered as an option)


DSP80 Series Instrument Components

Figure 1- 1The Model DSP80 is a convenient hand-held sound level meter with a simple user interface.

The standard Model DSP80 shown in Figure 1-1 includesthe following:

• A 10.6mm (1/2”) diameter precision microphone

• A 1/2” microphone preamplifier (PRM828)

• A 1/2” microphone (2551)

• A two-line, 32-character, high-contrast LCD display

Precision

LCD Display

Keypad

Communications

Microphone

and powerconnector

Microphonepreamplifier


• A 12-key membrane keypad

• An external 5-pin cable connector located at the base ofthe instrument with the pinout shown in figure Figure 1-2:

Figure 1-2 External 5-pin Cable Connector Pinout. Using cable CBL063 and related software (both of which are optional), the 5-pin connector is used both for external power and for the remote interface.

System Diagram

Figure 1-3 illustrates the acoustic-to-digital signal path inthe Model DSP80 series sound level meters. As you can see,incoming sound is first converted to an electrical signal bythe microphone at the tip of the preamp. This electrical sig-nal is in turn sampled by an analog-to-digital converter(ADC). The ADC translates the continuously varying analogsignal to a series of digital bits (zeros and ones) which accu-rately represent the original analog samples.

Pin 1—Ground

1

23

4

5

Pin 2—transmit data (output)

Pin 3—receive data (input)

Pin 4—External power, 9-16Vdc, internally fused at 0.5A (DSP80 requires less than 75mA)

Pin 5—DC output, 25mV/dB


Figure 1- 3System Diagram. The DSP80 series sound level meters convert an acoustic signal to an electrical signal and then to a digital signal.

At the heart of the DSP80 series sound level meters is a dig-ital signal processor (DSP) which performs operations onthis string of digital samples. The samples are filtered anddetected according to the current instrument settings (whichare established during the calibration process). The digitalsignal processor connects to the LCD screen and membranekeypad, allowing you to view the data and to give input andcontrol.

External power input and an RS-232 interface to computersare available through the five-pin connector at the base ofthe instrument.

Getting Started

This section outlines the steps you need to follow when youfirst receive and unpack the DSP80 series instrument. Thefollowing topics are covered:

• Unpacking and Inspection

• Accessories and Optional Equipment

• Connecting Internal or External Power

mic Hi ADC

x128

Filter

Lo ADC

DSP

Display

RS 232

Keyboard

DCOut

PowerExternal

Battery


• Environmental Considerations

• Data Retention

You will then be ready to use your new Model DSP80 seriessound level meter for actual measurements (as describedlater in Chapter 2 and 3 of this manual).

Unpacking and Inspection

Your Model DSP80 series sound level meter has beenshipped in protective packaging. Please verify the packagecontents with the following list (Accessories and OptionalEquipment) and retain the shipping containers for safe ship-ment at a future date. Report any damage or shortage imme-diately to Larson Davis, Inc. at (801)-375-0177.

If you have not already done so, please record at the begin-ning of this manual: a) your instrument’s serial number(located on the label on the back of the instrument), b) themicrophone serial number, and c) the purchase date (see thecopyright page). You will be asked to give this information inany future communications you may have with LarsonDavis, Inc.

Accessories and Optional Equipment

The DSP80 series sound level meter is delivered with thefollowing standard accessories:

• DSP80 series sound level meter (including preamp andmicrophone)

• Alkaline battery, 9 volts (IEC 6LR61 or NEDA/ANSI1604A)

A good quality alkaline cell should provide more than six hours of DSP80 operation. Since most rechargeable cells have less capacity, expect shorter use.

• Reference manual (LD part # I80.01)


• 22mm (3 and 1/2”) diameter windscreen (LD part #WS001)

Wind noise can adversely affect measurements. Using the windscreen on the microphone reduces wind noise and protects the element from dust and bumps.

The following optional equipment is also available:

• CAL200 Sound Level Calibrator

• CAL250 Sound Level Calibrator

• CBL063 cable (2.4m length) for external AC/DC poweradaptor and RS232 9-pin connection to personal com-puter

• PSA001, PSA002, or PSA027 115 or 220VAC to 9VDCpower adapters (for CBL063)

• CCS002 hard case (30 x 23 x 12cm)

Connecting Internal or External Power

To insert the 9 volt battery into the instrument, slide the bat-tery cover at the bottom side of the DSP80 series instrumenttowards the bottom of the meter. Place the battery into thecompartment with the terminals of the battery going in firstwith the proper polarity (refer to figure 1-4). Internal batterylife is approximately six hours. (Refer to the keydescription in Chapter 3)


Figure 1-4 Internal Battery Source

Alternatively, you may use an external power source via pin4 of the 5-pin connector. To do this, order cable CBL063from Larson Davis. The DSP80 series accepts 9-16 Vdc andis internally fused at 0.5 A.

Environmental Considerations

The DSP80 series sound level meters can be both used andstored in a wide range of temperatures if free of moistureand non-condensing humidity conditions (see “Environmen-tal” specifications in Appendix A of this manual). However,some common sense precautions should be taken. For exam-ple, allow the DSP80 series meter ample time to adjust toabrupt temperature changes. Condensation may form insidea cold instrument if it is brought into a warm room or vehicleand may persist long after the outside case has adjusted tothe ambient temperature.

Also, temperatures inside closed vehicles can reach exces-sive levels. Therefore, do not leave the instrument in directsunlight in a vehicle. A simple safeguard is to keep theinstrument inside a sealed foam insulated case or bag withdesiccant silica gel, available at photographic equipmentstores.


Data Retention

The DSP80 series sound level meters do not have a perma-nent measurement data memory. Each time the instrument isturned on, it is automatically reset for a new measurement.However, it will retain calibration data from the last calibra-tion. (Please contact Larson Davis for information on othersound level meters if your measurements require data log-ging and other capabilities.)

6/11/01 Instrument Keypads and Calibration 2-1

C H A P T E R

2 Instrument Keypads and Calibration

Once your DSP80 series sound level meter is unpacked andconnected to a battery (or external power supply), you canturn it on and take simple measurements. In this chapter, wediscuss the following:

• Understanding the DSP80 keypad




• Understanding the screen

• Turning on the instrument

* A precision calibrator is not necessaryfor this part of the tutorial, but youshould make it a regular practice to per-form an instrument calibration beforeand after you take critical measurementsin the field.

• Calibrating the instrument*


Understanding the DSP80 Keypad

The keypad for the DSP80 has 12 keys as seen in the follow-ing figure (Figure 2-1):

Figure 2-1 DSP80 Keypad.

These keys perform the following functions. (This informa-tion is covered in more detail in Chapter 4 of this manual.)

Turns on the DSP80. Once turned on, this button serves a “run” function for starting a measurement.

Turns off the DSP80.

Stops a measurement. If is then pressed immediately afterwards (instead of ), the key serves as a “pause” function.

WGHT

SLOW

BATT

LEQFAST

CAL

OFF RESET

ONSTOP

DIGITAL INTEGRATING SOUND LEVEL METER

LARSON•DAVIS DSP80

RUN

NOTE: The Model DSP80 momentarilypauses the current measurement whenever akey is pressed (in order to interpret the key-board event). Therefore, do not press a keyduring a valid event you wish to measure.


Restarts a measurement by erasing the values just measured. The function can be used whether a measurement is in the “run” or “stop” mode.

or

Changes the exponential time weighting to “fast”, or “slow”. The clock continues but the DSP80 pauses briefly between display changes.

Displays integrated sound level information (for selected frequency weightings A, B, or C) and Lpk (C-weighted) information. The clock continues but the DSP80 pauses briefly between display changes.

Changes frequency weighting to A, B, or C, for FAST, SLOW, and Leq (but not for Peak). Pressing this key performs a reset and restarts the clock.

Displays voltage level of the battery.

Used simultaneously with either the or arrow key to calibrate the DSP80.

or

Used simultaneously with the key to calibrate the DSP80.






WGHT

SLOW

OCT

LEQFAST

CAL

OFF RESET

ON BATT

STOP



RUN



NOTE: The Model DSP81 momentarilypauses the current measurement whenever akey is pressed (in order to interpret the key-board event). Therefore, do not press a keyduring a valid event you wish to measure.


.

Stops a measurement. If is then pressed immediately afterwards (instead of ), the key serves as a “pause” function. After depressing this button, select again and hold it down to test the battery level.


or


Displays integrated sound level information (for selected frequency weightings A, B, or C) and Lpk (C-weighted) information. The clock continues but the DSP81 pauses briefly between display changes.


Activates Octave Filters. Select the up or down arrow keys to scroll through filters from 31.5 Hz to 8 kHz.


or

Used simultaneously with the key to calibrate the DSP81. Also use to select an octave filter from 31.5 Hz to 8 kHz.






WGHT

SLOW

LEQ

IMPLFAST

CAL

OFF RESET

ON

STOP



RUNBATT



NOTE: The Model DSP82 momentarilypauses the current measurement when-ever a key is pressed (in order to inter-pret the keyboard event). Therefore, donot press a key during a valid event youwish to measure.




oror

Changes the exponential time weighting to “fast,” “slow,” or “impulse.” The clock con-tinues but the DSP82 pauses briefly between display changes.

Displays integrated sound level information (for selected frequency weightings A, B, or C), Lpk (unweighted), and octave filter infor-mation. The clock continues but the DSP82 pauses briefly between display changes.

Changes frequency weighting to A, B, or C, for FAST, SLOW, Impulse, and Leq (but not for Peak). Pressing this key performs a reset and restarts the clock.


or

Used simultaneously with the key to calibrate the DSP82. Also used to select octave filters from 31.5 Hz - 8kHz.




Figure 2-4 DSP83 Keypad




WGHT

SLOW

LEQ

IMPLFAST

CAL

OFF RESET

ON

STOP



RUNBATT

OCT

NOTE: The Model DSP83 momentarilypauses the current measurement when-ever a key is pressed (in order to inter-pret the keyboard event). Therefore, donot press a key during a valid event youwish to measure.




oror


Displays integrated sound level information (for selected frequency weightings A, B, or C) and Lpk (unweighted) information. The clock continues but the DSP83 pauses briefly between display changes.

Toggles between Octave Filters and Fre-quency Weighting for FAST, SLOW, IMPULSE, and Leq (but not for Peak). Press-ing this key performs a reset and restarts the clock.


or

Used simultaneously with the key to calibrate the DSP83. Also used to select A, B, or C frequency weighting, or to select octave filters from 31.5 Hz - 8kHz.


Understanding the DSP80 Series Screen

The operating screen for the DSP80 series meters have fieldswhich vary according to the keys pressed on the keypad, asseen in the following figure (Figure 2-5):

Figure 2-5 DSP80 Series Screen.

These 8 fields provide the following information:

Status

TimeWeighting

FrequencyWeighting Level

High Range/Noise Floor

Auxiliary Level/Leq Overload

pkC/ pkU/

Fast MAXElapsed Time/

Fast-Slow OverloadSlow MAX/

Status Figure depicting the states of running, stand-ing (pause), or sitting (stop).

TimeWeighting

Options are Leq, FAST, SLOW, and IMPULSE

FrequencyWeighting

Options are A, B, or C. Octave Filters are reported here when in the Octave Filter mode.

Level Value shown in tenths of decibels.

HighRange/NoiseFloor

High range options are “.” (indicating high range) and no symbol (indicating not high range). Noise floor options are “+N” (indicat-ing noise floor influenced) and no symbol (indicating not noise floor influenced).


Turning On the DSP80 Series Sound Level Meter

To turn on the Model DSP80 series sound level meter, fol-low these steps:

Step 1 Press the key. The DSP80 series meter will perform a self test showing automatically the following 4 displays:

Step 2 After approximately 1 second, the next display automatically appears:

AuxiliaryLevel\LeqOverload

Displays max level in tenths of decibels (when in FAST, SLOW, or IMPULSE mode), pkC level in tenths of decibels (when in Leq mode), or OVER (indicating pkC or pkU overload when in Leq mode).

pkC/Slow MAX/Fast MAX

Displays “pkC” or “pkU” (when in Leq mode), or “max” (when in FAST, SLOW, or IMPULSE mode).

ElapsedTime/Fast-SlowOverload

Shows elapsed time in hundredths of seconds (when in Leq, FAST, SLOW, or IMPULSE modes) or OVER (indicating overload when in FAST, SLOW, or IMPULSE modes).

This first display has copyrightinformation and appears for only 1to 2 seconds.

This second display shows the modelnumber (DSP80, 81, 82, or 83) andthe serial number (e.g., 0102) whichis uniquely assigned to your soundlevel meter. This message appearsfor only 1 to 2 seconds.


Step 3 After approximately 1 second, the next display automatically appears:

Step 4 After approximately 1 second, the fourth display automatically appears:

a. This display gives the initial default settings and is dis-played every time the instrument is turned on.

b. The stick figure in the upper left corner of the display is seated (meaning that the sound meter is in STOP/RESET mode). The figure can also be standing facing forward (indicating that the instrument is in STOP/PAUSE mode) or running (indicating it is in the RUN mode).

c. SLOW is the default exponential time weighting charac-teristic. It can be set by the user to FAST or IMPULSE

d. A is the default current frequency weighting. It can be set by the user to B or C.

e. “max” appears in the location next to where the highest (or maximum) measured value will appear once the key is pushed.

Step 5 At this point, you can change both the exponential time weighting and frequency weightings and begin taking actual measurements.

rev #

2.00 This third display shows the revisionnumber of the firmware (e.g., 2.00).This message appears for only 1 to 2seconds.


Calibrating the DSP80 Series Sound Meter

A sound level meter must be calibrated to a reference soundlevel for accurate measurements. This is easily performedwith the DSP80 series sound level meter. You will need acalibrator with an appropriate adapter for the microphone,such as the Larson Davis CAL200. This Larson Davis cali-brator outputs 94 or 114 dB with respect to 20µPa, and at afrequency of 1000 Hz. At this frequency, the relativeresponse for A, B and C weightings is the same.

Please note that if you use a calibrator which uses anotherfrequency, some corrections may be required depending onthe weighting. The output level and frequency of your cali-brator should be listed on its label. Use this level with speci-fied environmental and weighting corrections to calibratethe meter’s level. For example, the CAL200 label lists baro-metric pressure corrections to the nominal output.

NOTE: A precision calibrator is not nec-essary for this part of the tutorial, butyou should make it a regular practice toperform an instrument calibration beforeand after you take actual measurementsin the field. However, you do not have torecalibrate the instrument when youchange the settings (weighting, detector,time constant).

Step 1 Seat the microphone fully in the calibrator cavity and activate the tone on the calibrator.

Refer to the specific instructionsaccompanying your calibrator foraccomplishing this step.

Step 2 Press the key on the instrument keypad. Watch for a stable measurement (when the numeric value reaches a constant level) and then press. Information similar to the follow-ing appears:

Observe the level on the upper right of the display (in this example, “113.8”).


a. Once is pressed, the stick figure in the upper left of the display appears to be running.

b. Notice in this example that the exponential time weight-ing is set to FAST with a frequency weighting of C.

c. The “.” at the far right is the high range indicator, showing that the measurement is within the high range.*

Step 3 Press the and the or the arrow key buttons at the same time until the displayed level is correct. (In this case, press the arrow key twice while continuing to press the key so that the value changes from “113.8” to “114.0”.)

a. Each press of the or arrow keys changes the dis-played level by 0.1 dB.

b. Notice how the “max” value also changes by the same value (that is, from 113.8 dB to 114.0 dB).

c. If the symbol “+N” appears in the upper right corner of the display, the measurement is too close to the noise floor (i.e., 40 dB).

*The DSP80 series meters haveautomatic range switching andswitch between high and low rangesseamlessly. For meters with octavefilters the noise floor may be higherif out of band signals keep the instru-ment in the high range.

6/6/01 Simple Tutorial 3-1

C H A P T E R

3 Simple Tutorial

Your new DSP80 series sound level meter is designed tomeasure sound levels simply, quickly, and accurately. In thischapter, we discuss the following:

• Instrument - Functionality Matrix

• Functionality - Instrument Matrix

• Selecting a frequency weighting (A/B/C)

• Selecting exponential time weighting (FAST/SLOW)

• Checking the battery voltage

• Performing a measurement and reading the data

• Viewing Leq, LpkC, and LpkU

• Selecting octave filters (for DSP81 and DSP83 Meters)

• Pausing and resuming a measurement

• Stopping a measurement

• Turning off the DSP80 series sound level meter.

* A precision calibrator is not necessaryfor this part of the tutorial, but youshould make it a regular practice to per-form an instrument calibration beforeand after you take critical measurementsin the field.


Instrument - Functionality Matrix

The DSP80 series sound level meters have standard featureswhich meet domestic and international needs. Further, thedigital nature of the instruments allow for easy customiza-tion to meet special regulation requirements. The followingmatrix lists the four DSP80 series models, and identifieswhich features are available in each model.

Sound Level Meter Features and Functionality

DSP80 Slow and Fast RMS DetectorsC-weighted Peak Detector

Leq Integrated Level Measurement

DSP81 Slow and Fast RMS DetectorsC-weighted Peak Detector

Leq Integrated Level MeasurementOctave Filters (31.5 Hz - 8 kHz)

DSP82 Slow, Fast and Impulse RMS DetectorsUnweighted Peak Detector

Leq Integrated Level Measurement

DSP83 Slow, Fast and Impulse RMS DetectorsUnweighted Peak Detector

Leq Integrated Level MeasurementOctave Filters (31.5 Hz - 8 kHz)


Functionality - Instrument Matrix

The DSP80 series sound level meters have standard featureswhich meet domestic and international needs. Further, thedigital nature of the instruments allow for easy customiza-tion to meet special regulation requirements. The followingmatrix lists the standard features of the DSP80 series, andlists those instruments which possess each feature.

Features and Functionality Instrument

Leq Integrated Level Measurement DSP80DSP81DSP82DSP83

Octave Filters (31.5 Hz - 8 kHz) DSP81DSP83

Peak Detector, C-Weighted DSP80DSP81

Peak Detector, Unweighted DSP82DSP83

RMS Detector, Fast and Slow DSP80DSP81DSP82DSP83

RMS Detector, Impulse DSP82DSP83


Selecting a Frequency Weighting

During the calibration sequence, we used the default fre-quency weighting (which is A-weight). The DSP80 seriessound level meters also have B and C-weightings.

For the DSP80, 81, and 82: To select another weighting forthe DSP 80, 81, and 82, merely press the key onceor twice until the desired weighting appears on the display:

For the DSP83: For the DSP 83, use the or arrowkeys to select the A, B, or C-weightings.

Note that changing the weighting resets any measurementthat is currently running. This prevents you from incorrectlytaking a long term measurement with different frequencyweightings. (For a definition of frequency weightings andtheir use, please see Appendix C of this manual.)

Selecting Exponential Time Weighting

Thus far we have used SLOW exponential time weightingwhich is the default characteristic. However the DSP80series meters also have FAST and IMPULSE (available onthe DSP82 and DSP83) exponential time weighting. Unlikemany other meters, the DSP80 series meters can measureand alternatively display both FAST, SLOW, and IMPULSE(for the DSP82 and DSP83) time weighting while making ameasurement. To change the exponential time weighting,simply press the key one time. The display willshow the new (FAST or IMPULSE) exponential time


weighting:

NOTE: Remember, pushing a button canproduce small low-level noises whichcan affect your readings. In addition, theModel DSP80 series instrumentsmomentarily pause the current measure-ment whenever a key is pressed (in orderto interpret the keyboard event). There-fore, where possible, do not press a keyduring a valid event you wish to mea-sure.

Similarly, by pressing the key one time, the displaywill return to the SLOW exponential time weighting. Unlikea change in frequency weighting (A, B, or C), modifying theexponential time weighting will not reset the running mea-surement since FAST, SLOW, IMPULSE, Leq, and LpkC aresimultaneously being measured. However, there is amomentary pause in measurements between changes in set-tings. (For a definition of exponential time weighting char-acteristics and their use, please see the appropriate referencesection in Appendix C of this manual.)

Checking the Battery Voltage

The DSP80 series meters continuously monitor their batteryvoltage to ensure accurate measurements. Each has a batterylife of about six hours, and will turn off automatically whenthe voltage falls below 5.7 volts. Therefore you should ver-ify that the remaining battery capacity is sufficient beforeyou make an especially critical or lengthy measurement.

For the DSP80: To check battery voltage, simply press andhold down the key.

For the DSP81, 82, and 83: Select the key, and hold itdown until the reading appears on the screen. Informationsimilar to the following will display:


(Note: Checking the voltage during a measurement willpause the measurement while pressed.)

NOTE: Remember, pushing a button canproduce small low-level noises whichcan affect your readings. In addition, theDSP80 series meters momentarily pausethe current measurement whenever a keyis pressed (in order to interpret the key-board event). Therefore, where possible,do not press the key during avalid event you wish to measure.

In this example, there are 8.5 volts remaining in the battery.Assuming: a) that an internal alkaline cell drops from 9 voltsin a linear fashion; b) that the meter has a typical battery lifeof 6 hours; and c) that the meter automatically turns offbelow 5.7 volts; this 8.5 voltage reading would indicate thatthere are about 5 hours of remaining battery life.

Performing a Measurement and Reading the Data

Taking an measurement with the DSP80 series sound levelmeter is as easy as pressing the key. Rememberthough, for accurate measurements you always need to firstcalibrate your meter (as described earlier in this chapter).Once you press the key, the measurement beginsand continues indefinitely or until you press another key like , or. However, pressing the key during the RUN mode will immediately reset themeasurement values and then automatically begin run-ning a new measurement. In the example below, the expo-nential time weighting is FAST, using A frequencyweighting, with a current noise level of 72.9 dB, and a maxi-mum level of 78.4 dB.


Viewing L eq, LpkC and LpkU

The DSP80 series instruments are also integrating soundlevel meters. For DSP80 and DSP81 meters, the LpkC (C-weighted) is used, while the LpkU (Unweighted) is used. Touse this feature, simply press the key. Integrated levelinformation is then displayed as in the following example:

In this example, we see that the Leq is 56.9 dB(A), while thegreatest C-weighted peak level is 98.4 dB(pk). We also seethat the meter has been measuring for 52 seconds thus far.(The Leq duration can range from 1 second to 99 hours.)

NOTE: Remember, pushing a button canproduce small low-level noises whichcan affect your readings. In addition, theDSP80 series meters momentarily pausethe current measurement whenever a keyis pressed (in order to interpret the key-board event). Therefore, where possible,do not press a key during a valid eventyou wish to measure.

You can also press the key after you have pressed the key, in which case the elapsed time will show thetotal running time of the measurement, including the elapsedtime before the key was pressed.

Selecting Octave Filters (for DSP81 and DSP83 Meters)

The DSP81 and DSP83 have a special Octave Filter func-tion. In the DSP81, select the button, while in theDSP83 the key toggles between weight and OctaveFrequency, with the Octave Frequency being the default set-ting.

To select a frequency weighting in the 31.5 Hz - 8 kHzrange, use the following procedure:


Step 1 Select the appropriate key as described above.

Step 2 Use the or arrow keys to select the desired frequency weighting.

Step 3 Select the button, and the test will be per-formed automatically. When finished, select the button.

Pausing and Resuming a Measurement

There are times in taking a measurement when you need topause so an undesirable noise can pass by (for example, a jetflyover during a roadside noise test). To do this (for all mod-els in the DSP80 series), simply press the key, waitfor the undesirable event to pass, and then press the key. In the following example, we pause the measurement(by pressing the key) at 54 seconds:

The figure stands at 54 seconds, the elapsed time no longerincrements, and noise levels are not tallied. Once the unde-sirable noise passes, we resume the measurement by press-ing the key. The instrument continues themeasurement beginning at 54 seconds, and in this example,3 seconds later, displays the following information:


Stopping a Measurement

Elapsed time on the DSP80 series sound level meter isshown only for Leq measurements. Therefore, if you want tostop an Leq measurement precisely at 1 minute for example,simply press the key at the appropriate elapsed timeas in the following example:

In this example, the one minute Leq is 56.8 dB(A). (At thispoint, pressing the key resumes the measurement orpressing the key and then the key clears thevalues and starts a new measurement.)

Turning Off the DSP80 Series Meter

To turn off the DSP80 series sound level meter, simply pressthe key. All current data is erased and the frequencyand exponential time weighting options are returned todefault (A-weight, SLOW) when the instrument is subse-quently turned on again.

6/11/01 Reference 4-1

C H A P T E R

4 Reference

This chapter contains detailed information on the functionswhich are accessed through the DSP80 series keypads. (Thekeypads for each instrument are shown in Chapter 2.)

• Introduction

• Battery Key

• Calibrate, Up, and Down Arrow Keys

• Fast Exponential Time Weighting Key

• Impulse Key

• Integrating Sound Level Key

• Off Key

• On/Run Key

• Octave Filters

• Reset Key

• Slow Exponential Time Weighting Key

• Step Key

• Frequency Weighting Key


Introduction

Each of the DSP80 Series instruments contains similar func-tionality, with each having its own special features. A tabledetailing the functions of each instrument is contained inChapter 3. Each of the keys will be covered in the followingorder:

Displays voltage level of the battery.

and or

Used simultaneously with either the u or d arrow key to calibrate the DSP80 series meter.

Changes the exponential time weighting to “fast”. The clock continues but the DSP80 pauses briefly between display changes.

Activates the Impulse feature.

Displays integrated sound level information (for selected frequency weightings A, B, or C) and Lpk (C-weighted) information. The clock continues but the DSP80 series meter pauses briefly between display changes.

Turns off the DSP80 series meter.

Turns on the DSP80 series meter. Once turned on, this button serves a “run” function for starting a measurement.

Activates the Octave Filter feature.


Changes the exponential time weighting to “slow”. The clock continues but the DSP80 pauses briefly between display changes.


NOTE: The reference information in thischapter is organized according to func-tions, rather than by tasks which can useseveral functions. We therefore invite youto also read the tasks which are outlinedin the tutorial in Chapter 2 of this man-ual.

Any displays associated with the above keys will also bedescribed. In addition, relevant reference material will beincluded for any parameters or options which may be avail-able for keys on the DSP80 series keyboard.

Stops a measurement. If r is then pressed immediately afterwards (instead of ), the key serves as a “pause” function.


Changes frequency weighting as shown above, and also activates Octave feature.


B (Battery Key)

The purpose of the key on the DSP80 series meter isto display the remaining battery life. If you are using anexternal power supply, rather than a battery, the keywill merely display the constant voltage coming from thepower supply. The DSP80 series meter can operate forapproximately six hours when it is running from a new alka-line 9 volt battery. It will then turn off automatically whenthe battery voltage falls below 5.7 volts. Therefore youshould use the key to verify that there is sufficientbattery capacity before you make especially critical orlengthy measurements. To check battery voltage, it is best tofirst stop or pause any measurements, and then simply pressand hold down the key. Information similar to thefollowing will then display:

NOTE: Remember, pushing a button canproduce small low-level noises whichcan affect your readings. In addition, theDSP80 series meters momentarily pausethe current measurement whenever a keyis pressed (in order to interpret the key-board event). Therefore, where possible,do not press the key during avalid event you wish to measure.

In this example, there are 8.5 volts remaining in the battery.Assuming: a) that an alkaline battery drops from 9 volts in alinear fashion; b) that the meter has a typical battery life of 6hours; and c) that the meter automatically turns off below5.7 volts; this 8.5 voltage reading would indicate that thereare about 5 hours of remaining battery life.

C, u, d (Calibrate, Up, and Down Arrow Keys)

The and and arrow keys are used when cali-brating the DSP80 series meters. As with any sound levelmeter, you should make it a regular practice to perform aninstrument calibration before and after you take actual mea-surements in the field. However, you do not have to performa calibration when you change the meter’s settings (weight-ing, detector, time constant).


A sound level meter’s electronics must be calibrated to a ref-erence sound level for accurate measurements. This is easilyperformed with the DSP80 series meters. You will need acalibrator with an appropriate adapter for the microphone,such as the Larson Davis CAL200. This Larson Davis cali-brator outputs 94 or 114 dB with respect to 20µPa, and at afrequency of 1000 Hz. At this frequency, the relativeresponse for A, B and C weightings is the same.

Please note that if you use a calibrator which uses anotherfrequency, some corrections may be required depending onthe weighting. The output level and frequency of your cali-brator should be listed on its label. Use this level with speci-fied environmental and weighting corrections to calibratethe meter’s level. For example, the CAL200 label lists baro-metric pressure corrections to the nominal.

NOTE: For a detailed step-by-stepexample of calibrating the DSP80 seriesmeters, please refer to Chapter 2 in thismanual.

Once the DSP80 series meter is turned on and the micro-phone is seated in the calibrator cavity, press the andeither the or arrow key buttons at the same timeuntil the displayed level is correct. Each time you press the uor d arrow keys, the displayed level increases or decreasesby 0.1 dB.

F (Fast Exponential Time Weighting Key)

The DSP80 series meters can take measurements using bothFAST and SLOW exponential time weighting. However, theSLOW exponential time weighting is the default characteris-tic. (In other words, it is automatically selected each timeyou turn on the sound level meter.) The FAST exponentialtime weighting characteristic is typically used to measuresounds that fluctuate rapidly, like a vehicle or airplane passby, or earthmovers or other construction equipment wherethe load on the engine changes rapidly.

Exponential time weighting is the process by which digitalsnapshots of continuous sound levels are averaged to pro-duce discrete values. The FAST exponential time weightingtakes the same number of samples per second as the SLOWmethod, but in FAST mode the sound level meter responds


more quickly (125 milliseconds) to the change in soundbeing measured.

NOTE: For a definition of SLOW timeweighting and its proper use, please seethe appropriate reference section in thischapter.

If the word SLOW appears on the meter’s display, and youwish to change the exponential time weighting characteristicfrom SLOW to FAST, simply press the key onetime. The display will then show the changed (FAST) expo-nential time weighting characteristic, which it will then usein the ensuing measurements:

Unlike a change in frequency weighting (A, B, or C), modi-fying the exponential time weighting characteristic will notreset the running measurement.

I (Impulse)

The DSP80 series meters perform a variety of exponentialweightings. The key activates the meter’s IMPULSEexponential time weighting. Simply select this key, and thedisplay will automatically show the Impulse weighting.

L (Integrating Sound Level Key)

Each of the DSP80 series meters is both a simple sound levelmeter and an integrating sound level meter (meaning it cansum up sound energy over a fixed period of time). Equiva-lent continuous sound level (or Leq) is the continuous steadynoise level which has the same total weighted acousticenergy (A, B, or C) as the real fluctuating noise measuredover the same period of time.

To use the Leq feature, simple press and then press. Integrated sound level information is then displayed


showing five parameters as in the following example:

An explanation of the five parameters follows:

• In the upper left corner of the display is a picture of astick figure that appears to be running. It indicates that ameasurement is in progress (it is currently not paused).The stick figure can also appear to be in a seated posi-tion, indicating that the meter is in STOP or RESETmode (in other words, no measurement is in progress).Finally, the stick figure can also be standing facing for-ward, indicating that the meter is in a STOP/PAUSEmode (in other words, a measurement is in progress butmomentarily paused).

• Leq indicates that an integrating sound level measure-ment has been selected (instead of a simple sound levelmeasurement).

• A is frequency weighting (can also be B or C).

• 56.9 indicates that the frequency weighting currentlyselected on the DSP80 is A-weight (LeqA) and that theLeq is currently 56.9 dB. (For Leq measurements, fre-quency weights can also be set to B or C. See the appro-priate reference section in this chapter.)

• 98.4 pkC indicates that the greatest C-weighted peaklevel (LpkC) is 98.4dB. (The DSP80 only measures Lpkat C-weight.)

• 00:52 is the total elapsed time the measurement has beenrunning (in this case, 52 seconds). This value resets to00:00 if the or key is pressed (and theDSP80 series meter then automatically starts running anew measurement).

Therefore in this example, we see that the Leq is 56.9dB(A), while the greatest C-weighted peak level (LpkC) is


NOTE: You can also press the keyafter you have pressed the key,in which case the elapsed time will showthe total running time of the measure-ment, including the elapsed time beforethe key was pressed.

98.4 dB. We also see that the measurement has been runningso far for 52 seconds.

O (Off Key)

The key is used to turn off (or power down) theDSP80 series meters. To turn off the meter, simply press the key. All current measurement data are erased and thefrequency weighting and exponential time weighting will bereturned to their defaults (that is, A-weight, SLOW) whenthe meter is turned on again. (Once is pressed, theDSP80 series meter cannot be turned on again until after 2seconds have elapsed.)

r (On/Run Key)

The key serves two functions. It is used to turn onthe DSP80 series meter and also to start (or run) measure-ments. If the meter is off, when you first press the key the meter goes through a self check, briefly showingfour different displays. The first display appears for approxi-mately one second, and gives copyright information:

The second display then automatically appears, showing themodel number (DSP80), revision number (80A) and theserial number which is uniquely assigned to your DSP80series meter (e.g., 0102). This message appears for only 1 to2 seconds and looks like the following:


The third display then automatically appears, showing thefirmware revision number (2.00). This message appears foronly 1 to 2 seconds and looks like the following:

The fourth and final display then automatically appears,showing 4 parameters:

An explanation of the four parameters follows:

• In the upper left corner of the display is a picture of astick figure in a seated position. It indicates that theDSP80 series meter is in STOP or RESET mode (in otherwords, no measurement is in progress). The stick figurecan also be standing facing forward, indicating that themeter is in a STOP/PAUSE mode (in other words, a mea-surement is in progress but momentarily paused).Finally, the stick figure can appear to be running, indicat-ing that a measurement is in progress (and not paused).

• SLOW is the default option for the exponential timeweighting on the DSP80 series meter. The user can alsoselect FAST. (See the appropriate reference section in thischapter.)

rev #

2.00


• A is the default option for the frequency weighting on theDSP80 series meter. The user can also select B or C. (Seethe appropriate reference section in this chapter.)

• max appears in the location to the right of where thehighest (or maximum) measured value will appear oncethe key is pushed and a measurement begins.

This display remains unchanged and without actual dB val-ues until you select another function or begin a measure-ment. For example, if you press the key, followedby the key, a display similar to the followingappears:

In this display, the stick figure appears to be running (indi-cating that a measurement is in progress), and the current C-weight value is 113.8 dB with a maximum C-weight valuethus far of 115.7 dB.

t or (Octave Filters)

The DSP81 and DSP83 have a special Octave Filter func-tion. In the DSP81, select the button, while in theDSP83 the key toggles between weight and OctaveFrequency, with the Octave Filter being the default setting.

To select a frequency weighting in the 31.5 Hz - 8 kHzrange, use the following procedure:

Select the appropriate key as described above. Use the or arrow keys to select the desired frequency weighting.Select the button, and the test will be performed auto-matically. When finished, select the button.


R (Reset Key)

The key instantly stops a measurement and erasesthe values. If is pressed while a measurement isrunning, it will also automatically begin running a new mea-surement. The key resets both simple sound andintegrating sound (Leq/Lpk) level measurements.

S (Slow Exponential Time Weighting Key)

The DSP80 series meter can take measurements using bothSLOW and FAST exponential time weighting. However, theSLOW exponential time weighting is the default characteris-tic. (In other words, it is automatically selected each timeyou turn on the meter.)

Exponential time weighting is the process by which digitalsnapshots of continuous sound levels are averaged to pro-duce discrete values. The SLOW exponential time weightingtakes the same number of samples per second as the FASTmethod, but in SLOW mode the sound level meter respondsless quickly (1 second) to the change in sound being mea-sured.

If the word FAST appears on the meter’s display, and youwish to change the exponential time weighting characteristicfrom FAST to SLOW, simply press the key one time.The display will then show the changed (SLOW) exponen-tial time weighting characteristic, which it will then use inthe ensuing measurements:


NOTE: For a definition of FAST timeweighting and its proper use, please seethe appropriate reference section in thischapter.

Unlike a change in frequency weighting (A, B, or C), modi-fying the exponential time weighting characteristic will notreset the running measurement since it is only a variation inthe rate at which the DSP80 series meter responds to thesound.

s (Stop Key)

The key pauses a measurement that is in progressand lets you make one of two choices. If you merely wait fora few seconds (for example, to let an unwanted noise passby) and then press the key, the measurement con-tinues from the point in time where you originally pressed s.(Thus, the key has served a PAUSE function.) But, ifyou press before you press , the originalvalues are erased and an entirely new measurement begins.

W or (Frequency Weighting Key)

The DSP80 series meters have three frequency weightingoptions: A, B, and C. Each weighting uniquely simulates theresponse of the human ear at different levels. An explanationof each of these weightings follows:

• A-weight : This type of frequency weighting, expressedin dB(A), is generally used in noise ordinances and regu-latory environments. It is found in U.S. and internationalstandards.

• B-weight : This type of frequency weighting, expressedin dB(B), is not generally used, but may be found ininternational standards.

• C-weight : This type of frequency weighting, expressedin dB(C), may be found in U.S. and international stan-dards.

• The default frequency weighting for the DSP80 seriesmeter is A. (In other words, it is automatically selectedeach time you turn on the meter.) To change the fre-quency weighting of a measurement, simple press the W


key and you will move to the next weighting option inalphabetic order. For example, if you are currently usingB-weight, pressing will change the weightingfrom B to C; pressing a second time will changethe weighting from C to A; and pressing the keya third time will change the weighting from A to B.

If a simple measurement is in progress, pressing the key will change the weight and automatically restart themeasurement (protecting you from gathering an invalidmeasurement with different weightings). Similarly, if an Leqmeasurement is in progress, pressing the key willchange the weight, automatically restart the measurement,and reset the elapsed time value to 00:00).

If your instrument is a DSP 83, the button will togglebetween Weighting and the Octave Filter Feature. OctaveFilter is the default setting.

6/11/01 Remote Interface 5-1

C H A P T E R

5 Remote Interface

This chapter provides information necessary to use theremote interface on the Model DSP80 Series Sound LevelMeter. The remote interface port is located at the bottom ofthe instrument.

The Model DSP80 series instrument remote interface portuses an external 5-pin cable connector located at the base ofthe instruemnt with the pinout shown in Figure 5-1. To usethis interface, you must first obtain from Larson Davis theoptional CBL063 cable. The 5-pin connector is used both forexternal power and for the remote interface:

Figure 5- 1External 5-pin Cable Connector Pinout.

Pin 1—Ground

1

23

4

5

Pin 2—transmit data (output)

Pin 3—receive data (input)

Pin 4—External power, 9-16Vdc, internally fused at 0.5A (DSP80 requires less than 75mA)

Pin 5—DC output, 25mV/dB


Remote Commands

The optional CBL063 cable allows you to communicate tothe DSP8X series meters through the RS232 port. TheDSP8X is set internally to 9600 baud, 8 bit, no parity andone stop bit. Commands must be terminated with a CR/LFcombination. XON/XOFF handshaking is supported.

Q0 (Query)

ASCII screen dump. “Running Man” is R; “Standing Man” is P; “Reset Man” is Z.

Q1 (Query)

Read battery voltage.

Q2 (Query)

Read internal temperature.

S0 (State) Pause, Stop.

S1 (State) Run.

S2 (State) Reset.

W0 (Weight)

A-weight, reset.

W1 (Weight)

B-weight, reset.

W2 (Weight)

C-weight, reset.

D0 (Detector)

Fast.

D1 (Detector)

Slow.

D2 (Detector)

Leq

F0 31 Hz filter

F1 63 Hz filter

6/11/01 Remote Interface 5-3

F2 125 Hz filter

F3 250 Hz filter

F4 500 Hz filter

F5 1000 Hz filter

F6 2000 Hz filter

F7 4000 Hz filter

F8 8000 Hz filter

6/11/01 A-1

A P P E N D I X

A Specifications

This Appendix contains the specifications for the DSP80Series Sound Level Meter in the following order:

• General

• Type

• Reference Direction

• Primary Indicator Range

• Reference Level

• Frequency Weightings

• Detector Time Weightings

• Effects of Temperature

• Effects of Humidity

• Limits of Temperature and Humidity

• Microphone Extension Cables

• Calibration Procedure

• Positioning of Instrument & Observer for Best Measure-ments

• Limitations on Output Electrical Impedance

• Reference Frequency

• Warm-up Time

• Microphone Electrical Impedance

A-2 DSP80 Series Reference Manual 6/11/01

• EMC Compliance Testing

General

Linearity range: > 100 dB

Max RMS level: 120 dBA (typical) 140 dB with OPT 03

RMS noise floor: 9 dBA (typical) 29 dBA with OPT 03

Time weighting: Slow, Fast and Impulse (DSP82 andDSP83)

Frequency weighting: A, B, and C

Microphone: 1/2” electret

Octave filters (DSP81 & DSP83 only): 31.5 Hz to 8 kHz

DC output: 0-3 volts @ 600Ω (25 mV/dB)

Remote interface: RS232

Power supply:

9 VDC battery, 6 hr. operation (DSP80/81), 4 hr.operation (DSP81/83)

External: 9 to 16 VDC, 60 mA @ 12 VDC

Dimensions: 12.6” L x 3.3” W x 1.1” D

Weight: 12.5 oz. (389 g)

Standards Met:

IEC 60651 - 2000 Type 1

IEC 60804 - 2000

IEC 61260 - 2000 (DSP81/83 only)

ANSI S1.4 - 1983 Type 1

6/11/01 A -3

ANSI S1.11 - 1986 Type 1D (DSP81/83)

compliant

Accessories (included)

WS001: windscreen

9V akaline battery

Operator’s manual

Accessories (optional)

CBL063: RS232 and power cable

PSA001: 115 VAC to 9VDC power adapter

PSA002: 220 VAC to 9 VDC power adapter

PSA027: 90 - 264 VAC to 12 VDC power adapter

CAL200, CAL250: Acoustic calibrators

TRP001: Tripod

Type

The Larson Davis Model DSP80 Series Sound Level Meterswith attached electret microphone are type 1 integratingsound level meters.

Reference Direction

The reference direction is perpendicular to the plane of themicrophone diaphragm:


Primary Indicator Range

The primary indicator range is > 100 dB, typically 20 dBSPL to 120 dB SPL with the PRM828 preamp. With OPT 03(PRM80 preamp) the range is 40 dB SPL to 140 dB SPL.For pulses of crest factor, 10, maximum upper level is 103dB SPL and with OPT 03 the upper level is 123 dB SPL.Overload will be indicated for levels higher than these.

ReferenceDirection

6/11/01 A -5

Reference Level

The reference level is 114 dB SPL.

Frequency Weightings

For all instruments, the frequency weightings are A, B, andC. For the DSP81 and DSP83, octave frequency weightingsof 31.5 Hz to 8 kHz are also available.

Detector Time Weightings

The detector time weightings are Fast, Slow, and PEAK,with impulse available in the DSP82 and DSP83.

Effects of Temperature

SPL varies <.5 dB when the complete instrument is variedover the -100 C to 500 C temperature range referenced at 200

C and tested at 36% RH with a 1 kHz acoustic signal.Abnormal readings may be achieved when testing in temper-atures lower then -10° C or higher than 50° C.

Effects of Humidity

SPL varies <.5 dB when the complete instrument is variedover the 30% to 90% RH range (referenced at 50% RH).Tested at 400 C with a 1 kHz acoustic signal.


Limits of Temperature and Humidity

Permanent damage can occur when stored or operated above600 C or below -200 C. Condensation of moisture will makereadings inaccurate but will be correct when moisture hasdissipated.

Microphone Extension Cables

Microphone extension cables up to 20 feet can be used.

Calibration Procedure

Using a Larson Davis CAL200 calibrator, insert the DSP80series microphone fully into the calibrator. Set the calibratorto 114 dB SPL and push the instrument’s button.Once the instrument is on and stabilized, push the button again to start reading levels. Set the meter by holdingdown the button and pressing either the or button enough times to raise or lower the reading of themeter level until it reads 113.8 dB. Then, release the key. (See Chapter 2 in this manual for detailed directions forcalibrating the DSP80 series instrument.)

Positioning of Instrument & Observer for Measurements

Free field measurements can be made with the DSP80 seriesmeter held in one hand, with the arm extended away fromthe body, and sound incident on the microphone perpendicu-lar to the plane of the diaphragm. Better measurements canbe made with the DSP80 series meter on a tripod and aCBL063 cable to a computer used to take data. The com-puter and observer can therefore be in a different room.

6/11/01 A -7

Limitations on Output Electrical Impedance

The DC output (pin 5 of IO connector) has a source imped-ance of 2 kΩ. For minimal error, use instruments with > 1MΩ input impedance when making DC output readings.

Reference Frequency

The reference frequency is 1000 Hz.

Warm-up Time

The DSP80 series meter will not proceed to a running condi-tion until it is allowed to warm-up (approximately 3 sec-onds).

Microphone Electrical Impedance

The DSP80 series microphone capacitance is 18 pF. Use theLarson Davis ADP005 for electrical testing.

Preamp Connector Pin-out at Top of DSP8X

Pin 3—Power supply negative

1

23

45

Pin 4—Ground

Pin 1—Ground

Pin 5—Power supply positive

Pin 2—Signal input


EMC Compliance Testing

DSP80, DSP81, DSP82, DSP83

Compliance with the Electromagnetic Compatibil-ity (EMC) directives

EC 60651 Amendment 2 (2000): Sound level meters.

IEC 60804 Edition 2.0 (2000) Integrating-averaging soundlevel meters.

EN 50081-1 (1993): Generic emission standard. Part 1: Res-idential, commercial, and light industrial.

EN 50081-2 (1993): Generic emission standard. Part 2:Industrial environment.

CISPR22 (1993): Limits and methods of radio disturbancecharacteristics of information technology equipment. ClassB Limits.

FCC Part 15 Class B limits.

EN 50082-1 (1997): Generic immunity standard. Part 1:Residential, commercial, and light industrial.

EN 50082-2 (1995): Generic immunity standard. Part 2:Industrial environment.

Also complies with draft standards IEC 61672 Sound levelmeters Part-1 Specifications (draft date Jan, 2001) andSound level meters Part-2 Pattern evaluations (draft dateMay, 2001). DSP81 and DSP83 also comply with draft stan-dard IEC 61260 Amendment 1: Octave-band and fractional-octave-band filters (draft date March, 2000).

6/11/01 A -9

The conditions called for in these EMC standards are listed below:

The DSP80 was tested with a 74 dB acoustic signal in SLMmode, A weight, Fast.

The reference orientation is with the microphone facing theemissions/immunity antenna.

The following accessories are connected during testing:PRM828 preamplifier, 2551 microphone, CBL063 Externalpower & RS232 cable, and PSA027 AC to DC poweradapter.

The setting and configuration for greatest radio-frequencyemissions is A weight, Fast with all of the accessories listedabove connected.

The mode of operations and connecting devices that produceminimum immunity to power and radio frequency fields are:A weight, Fast with all of the accessories connected as listedabove.

A short was applied to the input of the DSP81 and DSP83for testing the bandpass filters (IEC 61260).

No degradation in performance or loss of functionality wasfound following the application of electrostatic discharges.

The method of mounting the instrument for acoustic testingis on a tripod.

6/8/01 B-1

A P P E N D I X

B Instrument and Microphone Response Curves for the DSP80, 81, 82, & 83

This appendix contains sample printouts of instrumentcurves and microphone response curves associated with theDSP80, 81, 82, & 83. The following is a list of the curvesprovided:

• Log Linearity, Differential Linearity, and Range Data

• Weighted Peak Linearity

• Certificate of A-Weight Electrical Conformance

• Certificate of B-Weight Electrical Conformance

• Certificate of C-Weight Electrical Conformance

• Results of Crest Factor Tests

• Results of Burst Tests

• Results of Detector Tests

• Relative SPL Awt Slow vs. Humidity @ 400 C

• Relative SPL Awt Slow vs. Temp @ 36% RH

• Relative SPL Awt Slow vs. Humidity Endurance @ 400 Cand 90% RH

• Certificate of 31.25 Hz Octave Filter Shape

• Certificate of 62.5 Hz Octave Filter Shape

B-2 DSP80 Series Reference Manual 6/8/01

• Certificate of 125 Hz Octave Filter Shape




• Certificate of 2 KHz Octave Filter Shape



• DSP80 Free-field response @ 00 with PRM80 preampand 2551 microphone

• DSP80 Free-field response @ 900 with PRM828 preamp,2551 microphone and random incident corrector

• DSP80 Random response with PRM828 preamp, 2551microphone and random incident corrector

• DSP80 Free-field response @ 00 with PRM828 preampand 2551 microphone

• DSP80 Random response with PRM828 preamp and2551 microphone

• DSP80 response with PRM828 preamp and 2551 micro-phone @ 1 kHz

• DSP80 response with PRM828 preamp and 2551 micro-phone @ 2kHz




6/8/01 B -3

Log Linearity, Differential Linearity and Range Data

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Log Linearity, Differential Linearity and Range Data

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's Log Linerarity A-weightedresponse was then electrically tested using a 1kHz sine wave from 0.0 dBSPL to 125.0 dBSPL in 1.0 dBincrements.

2.0 1.7 1.4

1.0 0.7 0.4

0.0 Error(dB)

-0.4 -0.7 -1.0

-1.4 -1.7 -2.0

0 10 20 30 40 50 60Level (dBSPL)

70 80 90 100 110 120 130

Levl Meas ErrdBSPL dBSPL dB----- ------ ----- 0.0 7.5 7.5 1.0 8.4 7.4 2.0 8.6 6.6 3.0 8.9 5.9 4.0 9.1 5.1 5.0 9.4 4.4 6.0 9.8 3.8 7.0 10.3 3.3 8.0 10.8 2.8 9.0 19.9 10.9 10.0 11.9 1.9 11.0 12.6 1.6 12.0 13.3 1.3 13.0 14.1 1.1 14.0 14.9 0.9 15.0 15.8 0.8 16.0 16.7 0.7 17.0 17.6 0.6 18.0 18.4 0.4 19.0 19.3 0.3 20.0 20.3 0.3 21.0 21.2 0.2




Levl Meas ErrdBSPL dBSPL dB----- ------ ----- 88.0 88.0 0.0 89.0 89.0 0.0 90.0 90.0 0.0 91.0 91.0 0.0 92.0 92.0 0.0 93.0 93.0 0.0 94.0 94.0 0.0 95.0 95.0 0.0 96.0 96.0 0.0 97.0 97.0 0.0 98.0 98.0 0.0 99.0 99.0 0.0100.0 100.0 0.0101.0 101.0 0.0102.0 102.0 0.0103.0 103.0 0.0104.0 104.0 0.0105.0 105.0 0.0106.0 106.0 0.0107.0 107.0 0.0108.0 108.0 0.0109.0 109.0 0.0

Levl Meas ErrdBSPL dBSPL dB----- ------ -----110.0 110.0 0.0111.0 111.0 0.0112.0 112.0 0.0113.0 113.0 0.0114.0 114.0 0.0115.0 115.0 0.0116.0 116.0 0.0117.0 117.0 0.0118.0 118.0 0.0119.0 119.0 0.0120.0 120.0 0.0121.0 121.0 0.0122.0 121.9 -0.1123.0 122.6 -0.4124.0 120.5 -3.5125.0 119.7 -5.3

Plotted per typical sensitivity of an 2551 electret microphone; 50 mV/Pa & 15 pF.

Overload occurs at 121.7 dBSPL.Primary indicator range: 103.6 dB (lower limit: 18.0 dBSPL to upper limit: 121.6 dBSPL).Dynamic range: 114.0 dB (noise floor: 7.6 dBSPL to upper limit: 121.6 dBSPL).

This instrument is in compliance with IEC 60651-1979 7.9 and 7.10, ANSI S1.4-1983 3.2 andIEC 60804-1985 9.2.1 for Type 1 sound level meters when used with a Larson Davis Type 1 microphone.

Technician: Leroy Harbaugh Test Date: May 25, 2001


Weighted Peak Linearity

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Weighted Peak Linearity

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's Weighted linearityresponse was then electrically tested using a 1kHz sine wave from 0 dBSPL to 125 dBSPL in 1.0 dB increments .

4.0

2.0

0.0 Error(dB)

-2.0

-4.0 0 10 20 30 40 50 60

Input Peak Level (dBSPL)70 80 90 100 110 120 130

Plotted per typical sensitivity of an 2551 electret microphone; 50 mV/Pa & 15 pF.


6/8/01 B -5

Certificate of A-Weight Electrical Conformance

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Certificate of A-Weight Electrical Conformance

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's A-weighted responsewas then electrically tested using a 0.9 Vrms sinewave at exact frequencies as specified in IEC 60651-1979and ANSI S1.4-1983.

5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

Level (dB)

-35.0

-40.0

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0 10 31.6 100 316.2 1000 3162 12500

Frequency (Hz)

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 10.00 -70.4 -70.00 0.40 +1.8, -1.8 12.59 -63.4 -63.00 0.40 +1.5, -1.5 15.85 -56.7 -56.40 0.30 +1.2, -1.2 19.95 -50.5 -50.30 0.20 +1.0, -1.0 25.12 -44.7 -44.70 0.00 +0.9, -0.9 31.62 -39.4 -39.40 0.00 +0.7, -0.7 39.81 -34.6 -34.70 -0.10 +0.7, -0.7 50.12 -30.2 -30.30 -0.10 +0.5, -0.5 63.10 -26.2 -26.20 0.00 +0.5, -0.5 79.43 -22.5 -22.50 0.00 +0.5, -0.5 100.00 -19.1 -19.20 -0.10 +0.5, -0.5 125.00 -16.1 -16.20 -0.10 +0.5, -0.5 158.50 -13.4 -13.40 0.00 +0.5, -0.5 199.50 -10.9 -10.90 0.00 +0.5, -0.5 251.20 -8.6 -8.60 0.00 +0.5, -0.5 316.20 -6.6 -6.60 0.00 +0.4, -0.4

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 398.10 -4.8 -4.80 0.00 +0.4, -0.4 501.20 -3.2 -3.20 0.00 +0.4, -0.4 631.00 -1.9 -1.90 0.00 +0.4, -0.4 794.30 -0.8 -0.80 0.00 +0.4, -0.4 1000.00 0.0 0.00 0.00 +0.4, -0.4 1259.00 0.6 0.60 0.00 +0.4, -0.4 1585.00 1.0 1.00 0.00 +0.4, -0.4 1995.00 1.2 1.20 0.00 +0.4, -0.4 2512.00 1.3 1.30 0.00 +0.4, -0.4 3162.00 1.2 1.20 0.00 +0.4, -0.4 3981.00 1.0 1.00 0.00 +0.4, -0.4 5012.00 0.5 0.60 0.10 +0.5, -0.5 6310.00 -0.1 -0.10 0.00 +0.5, -0.7 7943.00 -1.1 -1.10 0.00 +0.5, -1.0 10000.00 -2.5 -2.40 0.10 +0.7, -1.3 12590.00 -4.3 -4.30 0.00 +1.0, -2.0

This instrument is in compliance with IEC 60651-1979 6.1 and 9.2.2, ANSI S1.4-1983 5.1 and 8.2.1, andIEC 60804-1985 5.1 for Type 1 sound level meters when used with a Larson Davis Type 1 microphone.



Certificate of B-Weight Electrical Conformance

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Certificate of B-Weight Electrical Conformance

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's B-weighted responsewas then electrically tested using a 0.9 Vrms sinewave at exact frequencies as specified in IEC 60651-1979and ANSI S1.4-1983.

3.0

0.0

-3.0

-6.0

-9.0

-12.0

-15.0

-18.0

Level (dB)

-21.0

-24.0

-27.0

-30.0

-33.0

-36.0

-39.0

-42.0 10 31.6 100 316.2 1000 3162 12500

Frequency (Hz)

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 10.00 -38.2 -38.00 0.20 +1.8, -1.8 12.59 -33.2 -32.90 0.30 +1.5, -1.5 15.85 -28.5 -28.30 0.20 +1.2, -1.2 19.95 -24.2 -24.10 0.10 +1.0, -1.0 25.12 -20.4 -20.40 0.00 +0.9, -0.9 31.62 -17.1 -17.10 0.00 +0.7, -0.7 39.81 -14.2 -14.30 -0.10 +0.7, -0.7 50.12 -11.6 -11.70 -0.10 +0.5, -0.5 63.10 -9.3 -9.40 -0.10 +0.5, -0.5 79.43 -7.4 -7.50 -0.10 +0.5, -0.5 100.00 -5.6 -5.70 -0.10 +0.5, -0.5 125.00 -4.2 -4.30 -0.10 +0.5, -0.5 158.50 -3.0 -3.00 0.00 +0.5, -0.5 199.50 -2.0 -2.10 -0.10 +0.5, -0.5 251.20 -1.3 -1.40 -0.10 +0.5, -0.5 316.20 -0.8 -0.90 -0.10 +0.4, -0.4

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 398.10 -0.5 -0.50 0.00 +0.4, -0.4 501.20 -0.3 -0.30 0.00 +0.4, -0.4 631.00 -0.1 -0.10 0.00 +0.4, -0.4 794.30 0.0 -0.10 -0.10 +0.4, -0.4 1000.00 0.0 0.00 0.00 +0.4, -0.4 1259.00 0.0 0.00 0.00 +0.4, -0.4 1585.00 0.0 0.00 0.00 +0.4, -0.4 1995.00 -0.1 -0.10 0.00 +0.4, -0.4 2512.00 -0.2 -0.20 0.00 +0.4, -0.4 3162.00 -0.4 -0.40 0.00 +0.4, -0.4 3981.00 -0.7 -0.70 0.00 +0.4, -0.4 5012.00 -1.2 -1.20 0.00 +0.5, -0.5 6310.00 -1.9 -1.90 0.00 +0.5, -0.7 7943.00 -2.9 -2.90 0.00 +0.5, -1.0 10000.00 -4.3 -4.30 0.00 +0.7, -1.3 12590.00 -6.1 -6.10 0.00 +1.0, -2.0



6/8/01 B -7

Certificate of C-Weight Electrical Conformance

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Certificate of C-Weight Electrical Conformance

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's C-weighted responsewas then electrically tested using a 0.9 Vrms sinewave at exact frequencies as specified in IEC 60651-1979and ANSI S1.4-1983.

3.0

0.0

-3.0

-6.0

Level (dB)

-9.0

-12.0

-15.0

-18.0

-21.0 10 31.6 100 316.2 1000 3162 12500

Frequency (Hz)

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 10.00 -14.3 -14.10 0.20 +1.8, -1.8 12.59 -11.2 -11.10 0.10 +1.5, -1.5 15.85 -8.5 -8.40 0.10 +1.2, -1.2 19.95 -6.2 -6.10 0.10 +1.0, -1.0 25.12 -4.4 -4.40 0.00 +0.9, -0.9 31.62 -3.0 -3.10 -0.10 +0.7, -0.7 39.81 -2.0 -2.10 -0.10 +0.7, -0.7 50.12 -1.3 -1.50 -0.20 +0.5, -0.5 63.10 -0.8 -1.00 -0.20 +0.5, -0.5 79.43 -0.5 -0.60 -0.10 +0.5, -0.5 100.00 -0.3 -0.40 -0.10 +0.5, -0.5 125.00 -0.2 -0.30 -0.10 +0.5, -0.5 158.50 -0.1 -0.20 -0.10 +0.5, -0.5 199.50 0.0 -0.10 -0.10 +0.5, -0.5 251.20 0.0 -0.10 -0.10 +0.5, -0.5 316.20 0.0 0.00 0.00 +0.4, -0.4

Freq (Hz) Theor Measured Error LD Tolerance--------- ----- -------- ----- ------------ 398.10 0.0 0.00 0.00 +0.4, -0.4 501.20 0.0 0.00 0.00 +0.4, -0.4 631.00 0.0 0.00 0.00 +0.4, -0.4 794.30 0.0 0.00 0.00 +0.4, -0.4 1000.00 0.0 0.00 0.00 +0.4, -0.4 1259.00 0.0 -0.10 -0.10 +0.4, -0.4 1585.00 -0.1 -0.10 0.00 +0.4, -0.4 1995.00 -0.2 -0.20 0.00 +0.4, -0.4 2512.00 -0.3 -0.30 0.00 +0.4, -0.4 3162.00 -0.5 -0.50 0.00 +0.4, -0.4 3981.00 -0.8 -0.90 -0.10 +0.4, -0.4 5012.00 -1.3 -1.30 0.00 +0.5, -0.5 6310.00 -2.0 -2.10 -0.10 +0.5, -0.7 7943.00 -3.0 -3.00 0.00 +0.5, -1.0 10000.00 -4.4 -4.50 -0.10 +0.7, -1.3 12590.00 -6.2 -6.20 0.00 +1.0, -2.0




Results of Crest Factor Tests

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Results of Crest Factor Tests

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's C-weighted responseto specific crest factors was then electrically tested as specified in IEC 60651-1979 and ANSI S1.4-1983.

***** 200 uSec pulse tests at 2, 12, 22 & 32 dB below upper limit of 121.6 dBSPL *****

Pulse Type 1 Test OFF Ref Pos Pos Neg Neg Error Crest Level Pulse Time Level Pulse Pulse Pulse Pulse Tolerance Factor dBSPL VRMS Ampl (ms) dBSPL Level Error Level Error Limits ------ ----- ------ ------ ---- ------ ------ ----- ------ ----- ------- 3 119.7 0.9660 3.220 1.8 119.70 OVLD 0.00 OVLD 0.00 +/- 0.5 5 119.7 0.9660 5.023 5.0 119.70 OVLD 0.00 OVLD 0.00 +/- 1.0 10 119.7 0.9660 9.757 20.0 119.70 OVLD 0.00 OVLD 0.00 +/- 1.5

3 109.7 0.3055 1.018 1.8 109.70 109.40 -0.30 109.40 -0.30 +/- 0.5 5 109.7 0.3055 1.589 5.0 109.70 109.50 -0.20 109.40 -0.30 +/- 1.0 10 109.7 0.3055 3.085 20.0 109.70 OVLD 0.00 OVLD 0.00 +/- 1.5

3 99.7 0.0966 0.322 1.8 99.70 99.40 -0.30 99.40 -0.30 +/- 0.5 5 99.7 0.0966 0.502 5.0 99.70 99.40 -0.30 99.40 -0.30 +/- 1.0 10 99.7 0.0966 0.976 20.0 99.70 99.40 -0.30 99.40 -0.30 +/- 1.5

3 89.7 0.0305 0.102 1.8 89.70 89.40 -0.30 89.40 -0.30 +/- 0.5 5 89.7 0.0305 0.159 5.0 89.70 89.50 -0.20 89.40 -0.30 +/- 1.0 10 89.7 0.0305 0.309 20.0 89.70 89.40 -0.30 89.40 -0.30 +/- 1.5

This instrument is in compliance with IEC 60651-1979 9.4.2 and ANSI S1.4-1983 8.4.2.


6/8/01 B -9

Results of Burst Tests

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Results of Burst Tests

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's C-weighted responseto specific bursts was then electrically tested as specified in IEC 60651-1979 and ANSI S1.4-1983.

*** 2kHz tone burst (rep rate 40Hz) at 2, 12, 22 & 32 dB below upper limit of 121.6 dBSPL ***

Burst Burst Type 1 Test Cont Burst ON OFF Ref Meas Error Crest Level Ref Ampl Time Time Level Burst Burst Tolerance Factor dBSPL VRMS VRMS (ms) (ms) dBSPL Level Error Limits ------ ----- ------ ------ ---- ---- ------ ------ ------ ------- 3 119.7 0.9660 2.0722 5.5 19.5 119.70 OVLD 0.00 +/- 0.5 5 119.7 0.9660 3.4527 2.0 23.0 119.70 OVLD 0.00 +/- 1.0

3 109.7 0.3055 0.6553 5.5 19.5 109.70 109.70 0.00 +/- 0.5 5 109.7 0.3055 1.0918 2.0 23.0 109.70 109.80 0.10 +/- 1.0

3 99.7 0.0966 0.2072 5.5 19.5 99.70 99.70 0.00 +/- 0.5 5 99.7 0.0966 0.3453 2.0 23.0 99.70 99.70 0.00 +/- 1.0

3 89.7 0.0305 0.0655 5.5 19.5 89.70 89.70 0.00 +/- 0.5 5 89.7 0.0305 0.1092 2.0 23.0 89.70 89.70 0.00 +/- 1.0




Results of Detector Tests

Sound Level Meter Model: DSP80-PRM828 Serial Number: 760Results of Detector Tests

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's C-weighted DetectorBurst response was then electrically tested as specified in IEC 60651-1979 and ANSI S1.4-1983.

*** Slow detector tests 4,24&44 dB below upper limit of 121.6 dBSPL *** Test Ref Meas Type 1 Level Level Burst Level Actual Theor Tolerance dBSPL dBSPL Dur (ms) dBSPL Diff Diff Error Limits ----- ----- ----- ----- ----- ----- ----- ------- 117.7 117.80 500.0 113.80 -4.00 -4.10 0.10 -1.0 1.0 97.7 97.90 500.0 93.80 -4.10 -4.10 0.00 -1.0 1.0 77.7 77.80 500.0 73.80 -4.00 -4.10 0.10 -1.0 1.0

*** Fast detector tests 4,24&44 dB below upper limit of 121.6 dBSPL *** Test Ref Meas Type 1 Level Level Burst Level Actual Theor Tolerance dBSPL dBSPL Dur (ms) dBSPL Diff Diff Error Limits ----- ----- ----- ----- ----- ----- ----- ------- 117.7 117.80 200.0 116.80 -1.00 -1.00 0.00 -1.0 1.0 97.7 97.90 200.0 96.90 -1.00 -1.00 0.00 -1.0 1.0 77.7 77.80 200.0 76.90 -0.90 -1.00 0.10 -1.0 1.0



6/8/01B

-11

Relative S

PL A

wt S

low vs. H

umidity at 40

0 C

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

30 40 50 60 70 80 90 100

Re

lativ

e le

vel (

dB

)

Humidity (%)

DSP80A00760 at 114 dB and 1KHz

Relative SPL Awt Slow vs. Humidity at 40 degrees C

With an Electrostatic Actuator used to check levels

26 May 2001

B-12

DS

P80 S

eries Reference M

anual6/8/01

Relative S

PL A

wt S

low vs. Tem

p at 36% R

H

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

-10 0 10 20 30 40 50

Re

lativ

e le

vel (

dB

)

Temperature (deg C)


Relative SPL Awt Slow vs. Temp at 36% RH


26 May 2001

6/8/01B

-13

Relative S

PL A

wt S

low vs. H

umidity E

ndurance at 400 C

and 90% R

H

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

0 0.5 1 1.5 2 2.5

Re

lative

le

ve

l (d

B)

Hours of Humidity Endurance and reference check


Relative SPL Awt Slow vs. Humidity Endurance at 40 degrees C and 90% RH


26 May 2001

ref. check

36% RH

20 deg C


Certificate of 31.5 Hz Octave Filter Shape

Sound Level Meter Model: DSP81-PRM828 Serial Number: 132Certificate of 31.5 Hz Octave Filter Shape

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's 31.5 Hz filter responsewas then electrically tested using a 120.90 dBSPL sinewave at selected frequencies as specified in IEC 61260-1994.

5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 1.95 3.91 7.81 15.63 22.10 31.25 44.19 62.50 125 250 500

Frequency (Hz)

Freq (Hz) Measured Limits---------- -------- ---------------- 1.95 -80.90 -70.00, -inf 3.91 -77.80 -61.00, -inf 7.81 -49.30 -42.00, -inf 15.63 -21.10 -17.50, -inf 22.10 -3.80 -2.00, -5.00 24.10 -0.90 0.30, -1.30 26.28 0.00 0.30, -0.60 28.66 0.10 0.30, -0.40 31.25 0.10 0.30, -0.30

Freq (Hz) Measured Limits---------- -------- ---------------- 34.08 0.10 0.30, -0.40 37.16 0.00 0.30, -0.60 40.53 -0.90 0.30, -1.30 44.19 -3.80 -2.00, -5.00 62.50 -21.10 -17.50, -inf 125.00 -44.80 -42.00, -inf 250.00 -64.70 -61.00, -inf 500.00 -78.80 -70.00, -inf

This instrument is in compliance with IEC 61260-1994 (Class 1) and ANSI S1.11-1986 (Order 3, Type 1-D).


6/8/01 B -15

Certificate of 63 Hz Octave Filter Shape

Sound Level Meter Model: DSP81-PRM828 Serial Number: 132Certificate of 63 Hz Octave Filter Shape

This Type 1 Sound Level Meter (including PRM828 & ADP005 18 pF input adapter) wascalibrated with a reference 1kHz sine wave at a level of 114.0 dBSPL. The instrument's 63 Hz filter responsewas then electrically tested using a 120.90 dBSPL sinewave at selected frequencies as specified in IEC 61260-1994.

5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 3.91 7.81 15.63 31.25 44.19 62.50 88.39 125 250 500 1000

Frequency (Hz)

Freq (Hz) Measured Limits---------- -------- ---------------- 3.91 -78.40 -70.00, -inf 7.81 -68.90 -61.00, -inf 15.63 -44.90 -42.00, -inf 31.25 -21.10 -17.50, -inf 44.19 -3.90 -2.00, -5.00 48.19 -1.00 0.30, -1.30 52.56 -0.10 0.30, -0.60 57.31 0.00 0.30, -0.40 62.50 0.10 0.30, -0.30








5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 7.81 15.63 31.25 62.50 88.39 125 176.78 250 500 1000 2000

Frequency (Hz)

Freq (Hz) Measured Limits---------- -------- ---------------- 7.81 -78.30 -70.00, -inf 15.63 -64.30 -61.00, -inf 31.25 -44.90 -42.00, -inf 62.50 -21.20 -17.50, -inf 88.39 -4.00 -2.00, -5.00 96.39 -1.00 0.30, -1.30 105.11 -0.10 0.30, -0.60 114.63 0.10 0.30, -0.40 125.00 0.10 0.30, -0.30




6/8/01 B -17




5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 15.63 31.25 62.50 125 176.78 250 353.55 500 1000 2000 4000

Frequency (Hz)









5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 31.25 62.50 125 250 353.55 500 707.11 1000 2000 4000 8000

Frequency (Hz)





6/8/01 B -19




5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 62.50 125 250 500 707.11 1000 1414.21 2000 4000 8000 16000

Frequency (Hz)






Certificate of 2 kHz Octave Filter Shape



5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 125 250 500 1000 1414.21 2000 2828.43 4000 8000 16000 32000

Frequency (Hz)





6/8/01 B -21




5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 250 500 1000 2000 2828.43 4000 5656.85 8000 16000 32000 64000

Frequency (Hz)









5.0

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

-35.0

-40.0

Level (dB)

-45.0

-50.0

-55.0

-60.0

-65.0

-70.0

-75.0

-80.0

-85.0

-90.0 500 1000 2000 4000 5656.85 8000 11313.71 16000 32000 64000 128000

Frequency (Hz)

Freq (Hz) Measured Limits---------- -------- ---------------- 500.00 -80.50 -70.00, -inf 1000.00 -64.50 -61.00, -inf 2000.00 -45.00 -42.00, -inf 4000.00 -20.40 -17.50, -inf 5656.85 -3.40 -2.00, -5.00 6168.84 -0.60 0.30, -1.30 6727.17 0.00 0.30, -0.60 7336.03 -0.10 0.30, -0.40 8000.00 0.00 0.30, -0.30

Freq (Hz) Measured Limits---------- -------- ---------------- 8724.06 0.00 0.30, -0.40 9513.66 -0.10 0.30, -0.60 10374.72 -0.20 0.30, -1.30 11313.71 -3.80 -2.00, -5.00 16000.00 -78.20 -17.50, -inf 32000.00 -119.00 -42.00, -inf 64000.00 -119.40 -61.00, -inf 128000.00 -117.20 -70.00, -inf



6/8/01 B -23

DSP80 Free-field response @ 0 0 with PRM80 preamp and 2551 microphone


DSP80 Free-field response @ 90 0 with PRM828 preamp, 2551 microphone and random incident corrector

6/8/01 B -25

DSP80 Random response with PRM828 preamp, 2551 microphone and random incident corrector


DSP80 Free-field response @ 0 0 with PRM828 preamp and 2551 microphone

6/8/01 B -27

DSP80 Random response with PRM828 preamp and 2551 microphone


DSP80 response with PRM828 preamp and 2551 microphone @ 1 kHz

6/8/01 B -29


6/8/01 B -31



DSP80 response with PRM828 preamp and 2551 microphone @ 12.5 kHz

6/6/01 Glossary -1

A P P E N D I X

GlossaryThis appendix contains technical definitions of key acousti-cal and vibration terms commonly used with Larson Davisinstruments. The reader is referred to American NationalStandards Institute document S1.1-1994 for additional defi-nitions. Specific use of the terms defined are in the mainbody of the text.

Allowed Exposure Time (T i) It is the allowed time of exposure to sound of a constant A-weighted sound level given a chosen Criterion Level, Crite-rion Duration, and Exchange Rate. The equation for it is

where Lc is the Criterion Level, Tc is the Criterion Duration,Q is the Exchange Rate, K is the Exchange Rate Factor andLavg is the Average Sound Level.

Example: If Lc = 90, Tc = 8, Q = 3 and Li = 95 then

This means that if a person is in this area for 5 hours and 39minutes he will have accumulated a Noise Dose of 100%.Standard: ANSI S12.19

Average Sound Level (L avg) It is the logarithmic average of the sound during a Measure-ment Duration (specific time period), using the chosenExchange Rate Factor. Exposure to this sound level over theperiod would result in the same noise dose and the actual(unsteady) sound levels. If the Measurement Duration is thesame as the Criterion Duration, then Lavg=LTWA(LC)

Ti

TcLavg Lc–( ) Q⁄

2

-----------------------------------------Tc

Lavg Lc–( ) q⁄10

-----------------------------------------= =

Ti8

1095 90–( ) 10⁄

------------------------------- 8

295 90–( ) 3⁄

-------------------------- 5.656 = 5 hours and 39 minutes= = =

Lavg qLog101T--- 10

Lp t( )( ) q⁄

T1

T2

∫ dt

=

C

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-2 DSP80 Series Reference Manual 6/6/01

where the Measurement Duration (specified time period) isT=T2-T1 and q is the Exchange Rate Factor. Only sound lev-els above the Threshold Level are included in the integral.Standard: ANSI S12.19

Community Noise Equivalent Level (CNEL, L den)

A rating of community noise exposure to all sources ofsound that differentiates between daytime, evening andnighttime noise exposure. The equation for it is

The continuous equivalent sound level is generally calcu-lated on an hourly basis and is shown in the equation as L.The levels for the hourly periods from midnight to 7 a.m.have 10 added to them to represent less tolerance for noiseduring sleeping hours. The same occurs from 10 p.m. tomidnight. The levels for the hourly periods between 7 p.m.and 10 p.m. have 5 added to them to represent a lessened tol-erance for noise during evening activities. They are energysummed and converted to an average noise exposure rating.

Criterion Duration (T c) It is the time required for a constant sound level equal to theCriterion Level to produce a Noise Dose of 100%. CriterionDuration is typically 8 hours.Example: If the Criterion Level = 90 dB and the CriterionDuration is 8 hours, then a sound level of 90 dB for 8 hours,will produce a 100% Noise Dose. See Noise Dose. Standard:ANSI S12.19

Criterion Sound Exposure (CSE)

The product of the Criterion Duration and the mean squaresound pressure associated with the Criterion Sound Levelwhen adjusted for the Exchange Rate. It is expressed in Pas-cals-squared seconds when the exchange rate is 3 dB.where q is the Exchange Rate Factor. See Exchange Rate.

Standard: ANSI S1.25

Criterion Sound Level (L c) It is the sound level which if continually applied for the Cri-terion Duration will produce a Noise Dose of 100%. The

Lden

10log10 10Li 10+( ) 10⁄

0000

0700

∑ 10Li 10⁄

0700

1900

∑ 10Li 5+( ) 10⁄

1900

2200

∑ 10Li 10+( ) 10⁄

2200

2400

∑+ + +=

CSE Tc10Lc q⁄

=

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6/6/01 Glossary -3

current OSHA Criterion Level is 90 dB.Standard: ANSI S12.19

Daily Personal Noise Exposure (LEP,d)

It is the level of a constant sound over the Criterion Durationthat contains the same sound energy as the actual, unsteadysound over a specific period. The period is generally shorter,so the sound energy is spread out over the Criterion Durationperiod.Example: If the Criterion Duration = 8 hours and the specificperiod is 4 hours and the average level during the 4 hours is86 dB, then the LEP,d = 83 dB.

Day-Night Average Sound Level (DNL, L dn)

A rating of community noise exposure to all sources ofsound that differentiates between daytime and nighttimenoise exposure. The equation for it is

The continuous equivalent sound level (See definition) isgenerally calculated on an hourly basis and is shown in theequation as L. The values for the hourly periods from mid-night to 7 a.m. have 10 added to them to represent less toler-ance for noise during sleeping hours. The same occurs from10 p.m. to midnight. They are energy summed and convertedto an average noise exposure rating.

Decibel (dB) A logarithmic form of any measured physical quantity andcommonly used in the measurement of sound and vibration.Whenever the word level is used, this logarithmic form isimplied. The decibel provides us with the possibilty of rep-resenting a large span of signal levels in a simple manner asopposed to using the basic unit Pascal for e.g. acoustic mea-surements.

It is not possible to directly add or subtract physical quanti-ties when expressed in decibel form since the addition oflogarithmic values correspond to multiplication of the origi-nal quantitiy.

Ldn10Log10 10

Li 10+( ) 10⁄

0000

0700

∑ 10Li 10⁄

0700

2200

∑ 10Li 10+( ) 10⁄

2200

2400

∑+ +=

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The word level is normally attached to a physical quantitywhen expressed in decibels; for example, Lp represents thesound pressure level.

The difference between the sound pressure for silence versusloud sounds is a factor of 1,000,000:1 or more, and it is veryunpractical to use these large numbers. Therefore, a measurethat would relate to “the number of zeros” would help, forexample, 100,000 would be equal to 50 and 1000 would beequal to 30 and so on. This is the basic principal of the dBmeasure.

All dB values are unit free and therefore, the dB value is notthe value of the quantity itself, but the ratio of that quantityto an actual reference quantity used. Thus, for every level indecibels there must be a well defined reference quantity.Sound versus vibration uses different references, but the dBprincipal is the same. When the quantity equals the referencequantity the level is zero. To keep dB values above zero, thereference is generally set to be the lowest value of the quan-tity that we can imagine or normally wish to use. Beforeexplaining the calculation of dB values, it is useful toremember the following rules of thumb when dB values areused for sound levels:

- Doubling of the Sound Pressure = 6 dB

- Doubling of the Sound Power = 3 dB

- Doubling of the Perceived Sound Level = (approx) 10 dB

Note: The latter is frequency and level dependent, but thevalue “10 dB” is a good rule of thumb, especially around 1kHz.

Table 1 shows the actual value of a specific item, such assound power, for which the sound level is calculated. First,the sound power value is divided with the reference used andthen the ten-based logarithm is applied. This value is thenmultiplied by 10 to create the decibel value (see equation D-1 below).

For every 10 decibels, a unit called Bel is created. The deci-bel stands for: deci for “one tenth” and bel for “Bel” (com-pare decimeter). The relationship between Bel and decibel is

C

6/6/01 Glossary -5

thus: 1 Bel = 10 decibels. It is not possible to directly add orsubtract decibel values, since addition of logaritmic valuescorrespond to multiplication of the original quantity.

Each time the sound pressure level increases by 6 dB, thecorresponding sound pressure value is doubled and thusmultiplied by 2. Each time the sound power level increasesby 3 dB, the sound power value is multiplied by 2. Thus, it isimportant to notice that a doubling of the sound power isequal to 3 dB, and a doubling of the sound pressure is equalto 6 dB, since a doubling of the sound pressure will result ina quadruple increase of the sound power. The advantagewith using dB is simply that they remain the same even if weuse sound pressure or sound power. Compare this to the useof voltage and power units in electrical engineering, unitsbeing related by P~V2. In table 2 an illustration is made ofvalues calculated on sound pressure, non-squared units.

The original definition of decibel was intended for power-like quantities, such as sound power. If we consider soundpressure levels instead (usually denoted P in acoustics), theequation will be the same, since the “two” in the squaredunits will move from within the bracket and become a 20 loginstead of a 10 log and thus compensate for using linear orquadratic units. Please note that it is not allowed to use 20log for squared units, since that expression assumes that weuse linear units, like sound pressure in acoustics or voltage

Table 1Power form, squared units Level form

Ration of Value to ReferenceExponential Form of

Ratio10•Exponent

1 100 010 101 10

100 102 20200 102.3 23

1,000 103 3010,000 104 40

100,000 105 501000,000 106 60

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in electrical engineering. This is illustrated in equation D-1below:

Table 2 illustrates how a a tenfold increase of the soundpressure will result in an increase in 20 dB steps, whilesound power increases in 10 dB steps. See the linear form(Table 2) and compare with equation D-1. In conclusion, dBvalues are always the same, independent of using soundpower or sound pressure as the base unit. A 6 dB increaseimplies four times the sound power or two times the soundpressure.

Department of Defense Level (LDOD)

The Average Sound Level calculated in accordance withDepartment of Defense Exchange Rate and Threshold Level.See Average Sound Level

Dose (See Noise Dose)

Detector The part of a sound level meter that converts the actual fluc-tuating sound or vibration signal from the microphone to one

dB 10Log10P2

P02

-------- 20LogPP0

-----= = p; 0 20µPa=

Table 2Linear form, non-squared units Level form

Ration of Value to ReferenceExponential Form of

Ratio20•Exponent

1 100 010 101 20100 102 40200 102.3 46

1,000 103 6010,000 104 80100,000 105 100

1000,000 106 120

(eq. D-1)

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6/6/01 Glossary -7

that indicates its amplitude. It first squares the signal, thenaverages it in accordance with the time-weighting character-istic, and then takes the square root. This results in an ampli-tude described as rms (root-mean-square).

Eight Hour Time-Weighted Average Sound Level (L TWA(8))

It is the constant sound level that would expose a person tothe same Noise Dose as the actual (unsteady) sound levels.The equation for it is

NOTE: This definition applies only for a Criterion Durationof 8 hours. Standard: ANSI S12.19

Energy Equivalent Sound Level (Leq)

The level of a constant sound over a specific time period thathas the same sound energy as the actual (unsteady) soundover the same period.

where p is the sound pressure and the Measurement Dura-tion (specific time period) T=T2-T1. See Sound ExposureLevel.

Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k)

It is defined in ANSI S1.25 as “the change in sound levelcorresponding to a doubling or halving of the duration of asound level while a constant percentage of criterion expo-sure is maintained.” The rate and the factors are given inthe table below.Standard: ANSI S12.19

LTWA 8( ) Lc qLog10D

100---------

+=

Leq 10Log10

p2

t( ) tdT1

T2∫po

2T

--------------------------=

Exchange Rate, Q Exchange Rate Factor, q

Exposure Factor, k

3.01 10 14 13.333 .755 16.667 .60

6.02 20 .50

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Far Field There are two types of far fields: the acoustic far field andthe geometric far field.

Acoustic Far Field: The distance from a source of sound isgreater than an acoustic wavelength. In the far field, theeffect of the type of sound source is negligible. Since thewavelength varies with frequency (See the definition ofWavelength), the distance will vary with frequency. To be inthe far field for all frequencies measured, the lowest fre-quency should be chosen for determining the distance. Forexample, if the lowest frequency is 20 Hz, the wavelength atnormal temperatures is near 56 ft. (17 m); at 1000 Hz, thewavelength is near 1.1 ft. (1/3 m). See the definition ofAcoustic Near Field for the advantages of in the acoustic farfield.

Geometric Far Field: The distance from a source of sound isgreater than the largest dimension of the sound source. In thefar field, the effect of source geometry is negligible. Soundsources often have a variety of specific sources within them,such as exhaust and intake noise. When in the far field, thesources have all merged into one, so that measurementsmade even further away will be no different. See the defini-tion of Geometric Near Field for the advantages of being inthe geometric far field.

Free Field A sound field that is free of reflections. This does not meanthat the sound is all coming from one direction as is oftenassumed, since the source of sound may be spatially exten-sive. See the definitions of near and far fields for moredetail. This definition is often used in conjunction withreverberant field.

Frequency (Hz, rad/sec) The rate at which an oscillating signal completes a completecycle by returning to the original value. It can be expressedin cycles per second and the value has the unit symbol Hz(Hertz) added and the letter f is used for a universal descrip-tor. It can also be expressed in radians per second, which hasno symbol, and the greek letter ω is used for a universaldescriptor. The two expressions are related through theexpression ω=2Πf.

Frequency Band Pass Filter The part of certain sound level meters that divides the fre-quency spectrum on the sound or vibration into a part that is

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6/6/01 Glossary -9

unchanged and a part that is filtered out. It can be composedof one or more of the following types:

Low Pass: A frequency filter that permits signals to passthrough that have frequencies below a certain fixed fre-quency, called a cutoff frequency. It is used to discriminateagainst higher frequencies.

High Pass: A frequency filter that permits signals to passthrough that have frequencies above a certain fixed fre-quency, called a cutoff frequency. It is used to discriminateagainst lower frequencies.

Bandpass: A frequency filter that permits signals to passthrough that have frequencies above a certain fixed fre-quency, called a lower cutoff frequency, and below a certainfixed frequency, called an upper cutoff frequency. The differ-ence between the two cutoff frequencies is called the band-width. It is used to discriminate against both lower andhigher frequencies so it passes only a band of frequencies.

Octave band: A bandpass frequency filter that permits sig-nals to pass through that have a bandwidth based on octaves.An octave is a doubling of frequency so the upper cutoff fre-quency is twice the lower cutoff frequency. This filter isoften further subdivided in 1/3 and 1/12 octaves (3 and 12bands per octave) for finer frequency resolution. Instrumentswith these filters have a sufficient number of them to coverthe usual range of frequencies encountered in sound andvibration measurements.The frequency chosen to describethe band is that of the center frequency. Note table in Fre-quency Filter - Frequency Weighting.

Frequency Filter - Weighted A special frequency filter that adjusts the amplitude of allparts of the frequency spectrum of the sound or vibrationunlike band pass filters. It can be composed of one or moreof the following types:

A-Weighting: A filter that adjusts the levels of a frequencyspectrum in the same way the human ear does when exposedto low levels of sound. This weighting is most often used forevaluation of environmental sounds. See table below.B-Weighting: A filter that adjusts the levels of a frequencyspectrum in the same way the human ear does when exposedto higher levels of sound. This weighting is seldom used.

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See table below.C-Weighting: A filter that adjusts the levels of a frequencyspectrum in the same way the human ear does when exposedto high levels of sound. This weighting is most often usedfor evaluation of equipment sounds. See table below.Flat-Weighting: A filter that does not adjust the levels of afrequency spectrum. It is usually an alternative selection forthe frequency-weighting selection.

Leq See “Energy Equivalent Sound Level”, “Sound Level”,Energy Average”, and “Time Weighted Average”

Center Frequencies, Hz Weighting Network Frequency Response

1/3 Octave 1 Octave A B C20 -50.4 -24.2 -6.225 -44.7 -20.4 -4.4

31.5 31.5 -39.4 -17.1 -3.040 -34.6 -14.2 -2.050 -30.2 -11.6 -1.363 63 -26.2 -9.3 -0.880 -22.5 -7.4 -0.5100 -19.1 -5.6 -0.3125 125 -16.1 -4.2 -0.2160 -13.4 -3.0 -0.1200 -10.9 -2.0 0250 250 -8.6 -1.3 0315 -6.6 -0.8 0400 -4.8 -0.5 0500 500 -3.2 -0.3 0630 -1.9 -0.1 0800 -0.8 0 01000 1000 0 0 01250 0.6 0 01600 1.0 0 -0.12000 2000 1.2 -0.1 -0.22500 1.3 -0.2 -0.33150 1.2 -0.4 -0.54000 4000 1.0 -0.7 -0.85000 0.5 -1.2 -1.36300 -0.1 -1.9 -2.08000 8000 -1.1 -2.9 -3.010000 -2.5 -4.3 -4.412500 -4.3 -6.1 -6.216000 16000 -6.6 -8.4 -8.520000 -9.3 -11.1 -11.2

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6/6/01 Glossary -11

Level (dB) A descriptor of a measured physical quantity, typically usedin sound and vibration measurements. It is attached to thename of the physical quantity to denote that it is a logarith-mic measure of the quantity and not the quantity itself. Theword decibel is often added after the number to express thesame thing. When frequency weighting is used the annota-tion is often expressed as dB(A) or dB(B).

Measurement Duration (T) The time period of measurement. It applies to hearing dam-age risk and is generally expressed in hours.Standard: ANSI S12.19

Microphone Guidelines Microphone - Types: A device for detecting the presence ofsound. Most often it converts the changing pressure associ-ated with sound into an electrical voltage that duplicates thechanges. It can be composed of one of the following types:

Capacitor (Condenser): A microphone that uses the motionof a thin diaphragm caused by the sound to change thecapacitance of an electrical circuit and thereby to create asignal. For high sensitivity, this device has a voltage appliedacross the diaphragm from an internal source.Electret: A microphone that uses the motion of a thin dia-phragm caused by the sound to change the capacitance of anelectrical circuit and thereby to create a signal. The voltageacross the diaphragm is caused by the charge embedded inthe electret material so no internal source is needed.

Microphone - Uses: The frequency response of micro-phones can be adjusted to be used in specific applications.Among those used are:

Frontal incidence (Free Field): The microphone has beenadjusted to have an essentially flat frequency response whenin a space relatively free of reflections and when pointed atthe source of the sound.Random incidence: The microphone has been adjusted tohave an essentially flat frequency response for sound wavesimpinging on the microphone from all directions.Pressure: The microphone has not been adjusted to have anessentially flat frequency response for sound waves imping-ing on the microphone from all directions.

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What a microphone measures: A microphone detects morethan just sound. The motion of a microphone diaphragm isin

Microphone Guidelines, cont.response to a force acting onit. The force can be caused by a number of sources only oneof which are we interested: sound. Non-sound forces are: (1)direct physical contact such as that with a finger or a rain-drop; (2) those caused by the movement of air over the dia-phragm such as environmental wind or blowing; (3) thosecaused by vibration of the microphone housing; and (4)those caused by strong electrostatic fields.Rules:1. Do not permit any solid or liquid to touch the microphonediaphragm. Keep a protective grid over the diaphragm.2. Do not blow on a microphone and use a wind screen overthe microphone to reduce the effect of wind noise.3. Mount microphones so their body is not subject to vibra-tion, particularly in direction at right angles to the plane ofthe diaphragm.4. Keep microphones away from strong electrical fields.A microphone measures forces not pressures. We would likethe microphone to measure sound pressure (force per unitarea) instead of sound force. If the pressure is applied uni-formly over the microphone diaphragm a simple constant(the diaphragm area) relates the two, but if the pressure var-ies across the diaphragm the relationship is more complex.For example, if a negative pressure is applied on one-halfthe diaphragm and an equal positive pressure is applied tothe other half, the net force is zero and essentially no motionof the diaphragm occurs. This occurs at high frequencies andfor specific orientations of the microphone.Rules:1. Do not use a microphone at frequencies higher than speci-fied by the manufacturer; to increase the frequency responsechoose smaller microphones.2. Choose a microphone for free field or random incidenceto minimize the influence of orientation.A microphone influences the sound being measured. Themicrophone measures very small forces, low level sound canrun about one-billionth of a PSI! Every measurement instru-ment changes the thing being measured, and for very smallforces that effect can be significant. When sound impingesdirectly on a microphone the incident wave must bereflected since it cannot pass through the microphone. This

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6/6/01 Glossary -13

results in the extra force required to reflect the sound and amicrophone output that is higher than would exist if themicrophone were not there. This is more important at highfrequencies and when the microphone is facing the soundsource.Rules:1. Do not use a microphone at frequencies higher than speci-fied by the manufacturer; to increase the frequency responsechoose smaller microphones.2. Choose a microphone for free field or random incidenceto minimize the influence of orientation.A microphone measures what is there from any direction:Most measurements are intended to measure the sound levelof a specific source, but most microphones are not direc-tional so they measure whatever is there, regardless ofsource.Rules:1. When making hand-held measurements, keep your bodyat right angles to the direction of the sound you are inter-ested in and hold the meter as far from your body as possi-ble. Use a tripod whenever possible.2. Measure the influence of other sources by measuring thebackground sound level without the source of interest. Youmay have to correct for the background.

Near Field There are two types of near fields: the acoustic near fieldand the geometric near field.

Acoustic Near Field: The distance from a source of sound isless than an acoustic wavelength. In the near field, the effectof the type of sound source is significant. Since the wave-length varies with frequency (See the definition of Wave-length), the distance will vary with frequency. The mostcommon example of a near field is driving an automobilewith an open window. As you move your ear to the plane ofthe window, the sound pressure level builds up rapidly (windnoise) since most of the pressure changes are to move the airand very little of it compresses the air to create sound. Per-sons not far way, can hardly hear what you hear. The acous-tic near field is characterized by pressures that do not createsound that can be measured in the far field. Therefore mea-surements made here are not useful in predicting the soundlevels far way or the sound power of the source.

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Geometric Near Field: The distance from a source of soundis less than the largest dimension of the sound source. In thenear field, effect of source geometry is significant. Soundsources often have a variety of specific sources within them,such as exhaust and intake noise. When in the near field, thesound of a weaker, but close, source can be louder than thatof a more distant, but stronger, source. Therefore measure-ments made here can be used to separate the various sourcesof sound, but are not useful in predicting the sound levelsand sound spectrum far from the source.

Noise Typically it is unwanted sound. This word adds the responseof humans to the physical phenomenon of sound. Thedescriptor should be used only when negative effects onpeople are known to occur. Unfortunately, this word is usedalso to describe sounds with no tonal content (random):

Ambient: The all encompassing sound at a given locationcaused by all sources of sound. It is generally random, butneed not be.Background: The all encompassing sound at a given locationcaused by all sources of sound, but excluding the source tobe measured. It is essentially the sound that interferes with ameasurement.Pink: It is a random sound that maintains constant energyper octave. Pink light is similar to pink noise in that it has ahigher level at the lower frequencies (red end of the spec-trum). White: It is a random sound that contains equal energy ateach frequency. In this respect, it is similar to white light.

Noise Dose (D) It is the percentage of time a person is exposed to noise thatis potentially damaging to hearing. Zero represents no expo-sure and 100 or more represents complete exposure. It is cal-culated by dividing the actual time of exposure by theallowed time of exposure. The allowed time of exposure isdetermined by the Criterion Duration and by the sound level(the higher the level, the shorter the allowed time). Thesound levels must be measured with A-frequency weightingand slow exponential time weighting. See Projected NoiseDose.

D 100TTi

---- 100TTc

------------10Li Lc–( ) Q⁄

= =

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6/6/01 Glossary -15

where T is the Measurement Duration and Ti is the AllowedExposure Time.Standard: ANSI S12.19

Noise Exposure (See Sound Exposure)

OSHA Level (L OSHA) The Average Sound Level calculated in accordance with theOccupational Safety and Health Administration ExchangeRate and Threshold Level.

Preamplifier A part of the sound level meter that matches a particularmodel of microphone to the meter. It must be chosen in con-junction with a microphone and a cable that connects them.

Projected Noise Dose It is the Noise Dose expected if the current rate of noiseexposure continues for the full Criterion Duration period.

Single Event Noise Exposure Level (SENEL, L AX)

The total sound energy over a specific period. It is a specialform of the Sound Exposure Level where the time period isdefined as the start and end times of a noise event such as anaircraft or automobile passby.

Sound The rapid oscillatory compressional changes in a medium(solid, liquid or gas) that propagate to distant points. It ischaracterized by changes in density, pressure, motion, andtemperature as well as other physical quantities. Not allrapid changes in the medium are sound (wind noise) sincethey do not propagate.The auditory sensation evoked by the oscillatory changes.

Difference between sound and noise: Sound is the physicalphenomenon associated with acoustic (small) pressurewaves. Use of the word sound provides a neutral descriptionof some acoustic event. Generally, noise is defined asunwanted sound. It can also be defined as sound that causesadverse effects on people such as hearing loss or annoyance.It can also be defined as the sound made by other people. Inevery case, noise involves the judgment of someone andputs noise in the realm of psychology not physics.Rules: 1. Use word sound to describe measurements to remove theemotional overtones associated with the word noise. Somesound metrics use noise in their name and it is proper to usethe name as it is.

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Sound Exposure (SE) It is the total sound energy of the actual sound during a spe-cific time period. It is expressed in Pascals-squared seconds.

where pA is the sound pressure and T2 - T1 is the Measure-ment Duration (specific time period).When applied to hearing damage potential, the equation ischanged to

where k is the Exposure Factor. See Exchange Rate.Standard: ANSI S1.25

Sound Exposure Level (SEL, LET)

The total sound energy in a specific time period. The equa-tion for it is

The sound pressure is squared and integrated over a specificperiod of time (T2-T1) this is called the sound exposure andhas the units Pascal squared- seconds or Pascal squared-hours. P0 is the reference pressure of 20 µPa and T is the ref-erence time of 1 second. It is then put into logarithmic form.It is important to note that it is not an average since the refer-ence time is not the same as the integration time.

Sound Pressure The physical characteristic of sound that can be detected bymicrophones. Not all pressure signals detected by a micro-phone are sound (e.g., wind noise). It is the amplitude of theoscillating sound pressure and is measured in Pascals (Pa),Newtons per square meter, which is a metric equivalent ofpounds per square inch. To measure sound, the oscillatingpressure must be separated from the steady (barometric)pressure with a detector. The detector takes out the steadypressure so only the oscillating pressure remains. It then

SE pA2

t( ) td

T1

T2

∫=

SE pA2

t( )[ ]k

td

T1

T2

∫=

SEL 10Log10

p2 t( ) tdT1

T2

∫p0

2T

-------------------------=

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6/6/01 Glossary -17

squares the pressure, takes the time average, and then takesthe square root (this is called rms for root-mean square).There are several ways this can be done.

Moving Average: The averaging process is continuallyaccepting new data so it is similar to an exponential movingaverage. The equation for it is

The sound pressure is squared and multiplied by a exponen-tial decay factor so that when the time of integration is nearthe current time (t) it is essentially undiminished. For timesolder (less) than the current time, the value is diminishedand so becomes less important. The rate at which older dataare made less influential is expressed by the constant T. Thelarger is it the slower the decay factor reduces and the slowerthe response of the system to rapid changes. These are stan-dardized into three values called Time Weighting. See thevalues below.

Fixed Average: The averaging process is over a fixed timeperiod. The equation for it is

The sound pressure is squared and averaged over a fixedtime period. Unlike the moving average, the sound pressuresin all time intervals are equally weighted.

Sound Pressure Level (SPL, L p) The logarithmic form of sound pressure. It is also expressedby attachment of the word decibel to the number. The loga-rithm is taken of the ratio of the actual sound pressure to areference sound pressure which is 20 MicroPascals (µ Pa).There are various descriptors attached to this level depend-

prms1T--- p

2 ξ( )e t ξ–( ) T⁄– ξd

ts

t

∫=

prms1

T2 T1–( )----------------------- p

2t( ) td

T1

T2

∫=

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ing on how the actual sound pressure is processed in themeter:

Instantaneous: The time varying reading on a meter face onin a meter output due to changes in the sound pressure. Thereading will depend on the time-weighting applied.

The fundamental relationship between the two is logarithmic

where p0 is the reference sound pressure of 20 µPa. Thesquare of the sound pressure is a power-like quantity thatcan be expressed in the original form of the level definition

Sound Pressure Level can be converted to sound pressure asfollows. If the sound pressure is 1 Pascal, then the soundpressure level is

Calibrators often use a level of 94 dB so they generate asound pressure of 1 Pascal.

If the sound pressure level = 76.3 dB, then the sound pres-sure is

Energy Average (Leq): The value of a steady sound measuredover a fixed time period that has the same sound energy asthe actual time varying sound over the same period. Thisdescriptor is widely used. It is a fixed average (See SoundPressure).

Lp 20log10

prms

p0----------= prms p010

Lp 20⁄=

Lp 10log10

prms2

p02

----------= prms2 p0

210Lp 10⁄

=

Lp 20log101

20 10 6–•---------------------- 20log10 50000[ ] 20 4.699[ ] 94.0dB= = ==

Pa 20 106–• 10

76.3 20⁄• 20 103.815 6–• 20 10

2.185–• 20 0.0065[ ] 0.13= = = = =

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6/6/01 Glossary -19

Impulse: The value of an impulsive sound. The reading willdepend on the time-weighting applied.

Unweighted Peak: The peak value of a sound with a meterthat has flat frequency weighting and a peak detector.

Weighted Peak: The peak value of a sound with a meter thathas a frequency weighting other than flat and a peak detec-tor.

Sound Power(W) The sound power emitted by a sound source. It is measuredin Watts.

Sound Power Level (PWL, L w) The logarithmic form of sound power. It is also expressed byattachment of the word decibel to the number. The logarithmis taken of the ratio of the actual sound power to a referencesound power, which is 1 pico-watt. Sound power level can-not be measured directly, but can only be deduced throughmeasurements of sound intensity or sound pressure aroundthe source. The equation for it is

Sound Speed, (c,) The speed at which sound waves propagate. It is measuredin meters per second. It should not be confused with soundor particle velocity which relates to the physical motion ofthe medium itself.

Spectrum (Frequency Spectrum)

The amplitude of sound or vibration at various frequencies.It is given by a set of numbers that describe the amplitude ateach frequency or band of frequencies. It is often prefixedwith a descriptor that identifies it such as sound pressurespectrum. It is generally expressed as a spectrum level.

Lw 10log10WW0

-------= W W010Lw 10⁄

=

c 20.05 degC 273+= m sec⁄

c 49.03 degF 460+= ft sec⁄

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Threshold Sound Level (Lt) The A-weighted sound level below which the sound pro-duces little or no Noise Dose accumulation and may be dis-regarded. It is used for hearing damage risk assessment.Standard: ANSI S1.25

Time Weighted Average Sound Level (TWA, L TWA(TC))

It is the level of a constant sound over the Criterion Dura-tion, that would expose a person to the same Noise Dose asthe actual (unsteady) sound over the same period. If theExchange Rate is 3 dB then the TWA is equal to the Leq.

where Tc=T2-T1 and K is the Exchange Rate Factor. It isused for hearing damage risk assessment.Standard: ANSI S12.19

Time Weighting The response speed of the detector in a sound level meter.There are several speeds used.

Slow: The time constant is 1 second (1000 ms). This is theslowest and is commonly used in environmental noise mea-surements.Fast: The time constant is 1/8 second (125 ms). This is a lesscommonly used weighting but will detect changes in soundlevel more rapidly.Impulse: The time constant is 35ms for the rise and 1.5 sec-onds (1500 ms) for the decay. The reason for the double con-stant is to allow the very short signal to be captured anddisplayed.

Vibration The oscillatory movement of a mechanical system (gener-ally taken to be solid). It is used as a broad descriptor ofoscillations.

Wavelength (l) The distance between peaks of a propagating wave with awell defined frequency. It is related to the frequency throughthe following equation

LTWA TC( ) Klog101T--- 10

Lp t( )( ) K⁄td

T1

T2

∫

=

λ cf--=

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6/6/01 Glossary -21

where c is the sound speed and f is the frequency in Hz. Ithas the dimensions of length.

Wavenumber (k) A number that is related to the wavelength of sound and isused to compare the size of objects relative to the wave-length or the time delay in sound propagation. It is related towavelength through the following equation

where λ is the wavelength, c is the sound speed, f is the fre-quency in Hz, and ω is the radian frequency. It has thedimensions of inverse length.

k2πλ

------ 2πfc

-------- ωc----= = =

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-22 DSP80 Series Reference Manual 6/6/01C


i

AAmerican National Standards Institute (ANSI)

1-3auxiliary level

screen display .................................. 2-11

Bbattery

internal life of .................................. 1-9key ................................................... 4-4voltage, directions for checking ...... 3-5

CCAL200

calibrator .......................................... 2-13calibrate .................................................. 2-3,

2-5, 2-7, 2-9key ................................................... 4-4

calibratingdetailed directions for ...................... 2-13

Calibration .............................................. C-1calibration ............................................... 1-4,

1-11calibration procedure

specifications ................................... A-6calibrator

CAL200 ........................................... 1-9, 2-13, 4-5

CAL250 ........................................... 1-9commands

remote interface connector .............. 5-2Criterion .................................................. C-2

sound level ....................................... C-2

DDecibel .................................................... C-3Department of Defense

level ................................................. C-6Detector .................................................. C-6detector time weightings

specifications ................................... A-5digital signal processing

DSP ................................................. 1-1digital signal processor

DSP ................................................. 1-7down arrow

key ................................................... 4-4DSP

digital signal processing .................. 1-1digital signal processor .................... 1-7

DSP80keypad ............................................. 2-2

DSP80 Seriescalibrating ........................................ 2-13components ..................................... 1-5features ............................................ 1-3optional equipment .......................... 1-9screen .............................................. 2-10system diagram ............................... 1-6turning on ........................................ 2-11

DSP81keypad ............................................. 2-4

DSP82keypad ............................................. 2-6

DSP83keypad ............................................. 2-8

Durationmeasurement ................................... C-11

dynamic range ........................................ 1-3

Eelapsed time

screen display .................................. 2-11electret microphone ................................ 1-4,

1-5EMC

protection ........................................ 1-4EMI

protection ........................................ 1-4Exchange Rate

glossary ........................................... C-7

Index


ii

Exchange Rate Factorglossary ............................................ C-7

exponential time weighting .................... 1-4, 2-3, 2-5, 2-7, 2-9

FAST ............................................... 3-4FAST key ........................................ 4-5selecting ........................................... 3-4SLOW .............................................. 3-4SLOW default ................................. 4-10

Exposure Factorglossary ............................................ C-7

FFar Field .................................................. C-8

acoustic ............................................ C-8geometric ......................................... C-8

FASTexponential time weighting ............. 3-4

fast maxscreen display .................................. 2-11

fast-slow overloadscreen display .................................. 2-11

formatting conventions, of user manual . 1-2Free field ................................................. C-8Frequency

band pass filter ................................ C-8glossary ............................................ C-8Hz, rad/sec ....................................... C-8

frequency weighting ............................... 2-10A default .......................................... 4-10

defaultA frequency weighting 4-13

directions for selecting .................... 3-4key ................................................... 4-12

frequency weightings .............................. 1-3, 2-3, 2-5, 2-7, 2-9

specifications ................................... A-5

Hhigh range

screen display .................................. 2-10humidity


IIEC free-field response ........................... 1-4impulse ................................................... 4-6integrating sound level

key ................................................... 4-6International Electrotechnical Commission (IEC)

1-3

Kkey

battery .............................................. 4-4calibrate ........................................... 4-4down arrow ..................................... 4-4FAST exponential time weighting .. 4-5frequency weighting ........................ 4-12octave filters .................................... 4-10off .................................................... 4-8on/run .............................................. 4-8reset ................................................. 4-11run ................................................... 4-8SLOW exponential time weighting . 4-11stop .................................................. 4-12up arrow .......................................... 4-4

keypadDSP80 ............................................. 2-2DSP81 ............................................. 2-4DSP82 ............................................. 2-6DSP83 ............................................. 2-8

keysfunctions of DSP80 ......................... 2-2functions of DSP81 ......................... 2-4functions of DSP82 ......................... 2-6functions of DSP83 ......................... 2-8

LLeq .......................................................... 1-4

directions for viewing ..................... 3-7glossary ........................................... C-7

Leq overloadscreen display .................................. 2-11

Level ....................................................... C-11Dept of Defense .............................. C-6

level


iii

screen display .................................. 2-10Lpk

directions for viewing ...................... 3-7

Mmeasurement

directions for pausing and resuming 3-8directions for performing ................ 3-6directions for stopping ..................... 3-9

Microphoneguidelines ........................................ C-11what it measures .............................. C-12

microphone electrical impedancespecifications ................................... A-7

microphone extension cablesspecifications ................................... A-6

microphone reference number ................ 1-8Microphones

capacitor .......................................... C-11electrit .............................................. C-11uses .................................................. C-11

Model 820Glossary, App C .............................. C-1

NNear Field

acoustic ............................................ C-13geometric ......................................... C-14glossary ............................................ C-13

Noiseambient ............................................ C-14Background ..................................... C-14daily personal exposure ................... C-3dose(D) ............................................ C-14exposure .......................................... C-15glossary ............................................ C-2,

C-14pink .................................................. C-14projected noise dose ........................ C-15single event exposure level(SENEL,Lax)

C-15white ................................................ C-14

noise floorscreen display .................................. 2-10

Ooctave filters ........................................... 3-1

key ................................................... 4-10off

key ................................................... 4-8on/run

key ................................................... 4-8OSHA

level ................................................. C-15output electrical impedance


PPEAK detector ........................................ 1-4pkC

screen display .................................. 2-11positioning of instrument

specifications ................................... A-6power source

external ............................................ 1-10Preamplifier ............................................ C-15primary indicator range


Rreference direction

specifications ................................... A-3reference frequency

specifications ................................... A-7reference level

specifications ................................... A-5remote interface ...................................... 5-1remote interface connector

commands ....................................... 5-2reset

key ................................................... 4-11rms (root-mean-square) .......................... 1-4RS-232 .................................................... 1-4

Ssample instrument curve

Certificate of 1000 Hz Octave Filter Shape B-19


iv


Certificate of 2 KHz Octave Filter Shape B-20, B-28

Certificate of 250 Hz Octave Filter Shape B-17, B-24

Certificate of 31.25 Hz Octave Filter Shape B-14

Certificate of 4 KHz Octave Filter Shape B-21


Certificate of 62.5 Hz Octave Filter Shape B-15

Certificate of 8 KHz Octave Filter Shape B-22

Certificate of A-Weight Electrical Conformance B-5

Certificate of B-Weight Electrical Conformance B-6

Certificate of C-Weight Electrical Conformance B-7

Log Linearity, Differential Linearity and Data Range ........................ B-3

Relative SPL Awt Slow vs. Humidity at 40 C. B-11

Relative SPL Awt Slow vs. Temp at 36% RH B-12

Results of Burst Tests ...................... B-9, B-27, B-28, B-29, B-30, B-31, B-32

Results of Crest Factor Tests ........... B-8Results of Detector Tests ................. B-10Weighted Peak Linearity ................. B-4

sample instrument curves for DSP80-83 B-1screen display

auxiliary level .................................. 2-11elapsed time ..................................... 2-11fast max ........................................... 2-11fast-slow overload ........................... 2-11high range ........................................ 2-10Leq overload .................................... 2-11level ................................................. 2-10noise floor ........................................ 2-10pkC .................................................. 2-11

slow max ......................................... 2-11screen field

status ................................................ 2-10time weighting ................................. 2-10

serial number .......................................... 1-8SLOW

exponential time weighting ............. 3-4exponential time weighting key ...... 4-11

slow maxscreen display .................................. 2-11

Soundaverage level (lavg) ......................... C-1day-night average level ................... C-3energy average(Leq) ....................... C-18exposure .......................................... C-16exposure level ................................. C-16fixed average ................................... C-17glossary ........................................... C-15impulse ............................................ C-18instantaneous ................................... C-18intensity(l) ....................................... C-19moving average ............................... C-17pressure ........................................... C-16sound pressure level(SPL,Lp) ......... C-17unweighted peak ............................. C-18weighted peak ................................. C-19

Sound Levelthreshold(Lt) .................................... C-20

Sound Power .......................................... C-19level(PWL,Lw) ............................... C-19

Sound Pressure Level (see Sound) ......... C-17Sound Speed ........................................... C-19specifications .......................................... A-1

calibration procedure ....................... A-6detector time weightings ................. A-5frequency weightings ...................... A-5humidity .......................................... A-5microphone electrical impedance .... A-7microphone extension cables .......... A-6output electrical impedance ............ A-7positioning of instrument ................ A-6primary indicator range ................... A-4reference direction ........................... A-3reference frequency ......................... A-7reference level ................................. A-5


v

temperature ...................................... A-5type .................................................. A-3warm-up time .................................. A-7

Spectrumfrequency ......................................... C-19

statusscreen field ...................................... 2-10

stopkey ................................................... 4-12

STOP/PAUSEmode ................................................ 4-9

STOP/RESETmode ................................................ 4-9

system diagramDSP80 Series ................................... 1-6

Ttemperature

specifications ................................... A-5Time

allowed Exposure time(Ti) .............. C-1weighting ......................................... C-20

time weightingscreen field ...................................... 2-10

turning offdirections for ................................... 3-9

TWAtime weighted average (TWA, LTWA(TC)

C-20type

specifications ................................... A-3Type 1 ..................................................... 1-3

Uup arrow

key ................................................... 4-4

VVibration ................................................. C-20

Wwarm-up time


warranty .................................................. 1-4Wavelength(l)

glossary ........................................... C-20Wavenumber

glossary ........................................... C-21Weighted

8-hour time weighted average sound level C-7

Weightingfrequency ......................................... C-9time .................................................. C-20

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