hole farm, westfield lane, westfield, tn35 4sa

Hole Farm, Westfield Lane, Westfield, TN35 4SA

Materials Processing Facility Noise Assessment

August 2013

Waterman Energy, Environment & Design Limited

Pickfords Wharf, Clink Street, London SE1 9DG, www.watermangroup.com \\Nt_server\transfer\WEED - Reformatted Reports\EED Report - Preliminary Environmental Risk Assessment.dotm


Materials Processing Facility Noise Assessment

Client Name: Mr Robin Bristow

Document Reference: EED12597-103-R-1.1.6-LE

Project Number: EED12597

Our Markets

Property & Buildings Transport & Infrastructure Energy & Utilities Environment

Quality Assurance – Approval Status

This document has been prepared and checked in accordance with Waterman Group’s IMS (BS EN ISO 9001: 2008, BS EN ISO 14001: 2004 and BS OHSAS 18001:2007))

Issue Date Prepared by Checked by Approved by

001 July 2013 Laurence Evans Principal Acoustician

Innes Urbanski Senior Acoustician

Mark Maclagan Associate Director

002 September 2013 Laurence Evans Principal Acoustician



Disclaimer

This report has been prepared by Waterman Energy, Environment & Design Limited, with all reasonable skill, care and diligence within the terms of the Contract with the client, incorporation of our General Terms and Condition of Business and taking account of the resources devoted to us by agreement with the client.

We disclaim any responsibility to the client and others in respect of any matters outside the scope of the above.

This report is confidential to the client and we accept no responsibility of whatsoever nature to third parties to whom this report, or any part thereof, is made known. Any such party relies on the report at its own risk.


Contents

Contents

Executive Summary

1. Introduction ............................................................................................................................................ 1 2. Site and Development Description ...................................................................................................... 2

2.1 Site Description ........................................................................................................................... 2 2.2 Development Description ............................................................................................................ 2 2.3 Consultation ................................................................................................................................ 2

3. Assessment Criteria .............................................................................................................................. 4 3.1 Condition 3 of Planning Consent RR/700/CM ............................................................................ 4 3.2 The Concept of Noise, Disturbance and Annoyance .................................................................. 4

4. Noise Survey & Assessment Results .................................................................................................. 5 4.1 Assessment of Operational Impacts ........................................................................................... 5 4.2 Determination of Crusher Sound Power Level ........................................................................... 5 4.3 Predicted Noise Level at 115 Westfield Lane ............................................................................. 6 4.4 Simultaneous Source and Receiver Noise Levels ...................................................................... 6

5. Conclusions ........................................................................................................................................... 9

Figures

Figure 1: Location Plan of the Site, Receptor and Survey Positions

Tables

Table 1: Noise Sensitive Receptors ............................................................................................................... 2 Table 2: Summary of Permitted Hours of Use................................................................................................ 2 Table 3: Measured Mobile Crusher Noise Emission Levels at 10m and 20m ............................................... 5 Table 4: Predicted Noise Level of Mobile Crusher at 115 Westfield Lane ..................................................... 6

Appendices

Appendix A Glossary of Acoustic Terminology


Executive Summary

EXECUTIVE SUMMARY

SCOPE

Purpose of the Report

Assessment of noise from the proposed operation of a replacement mobile crusher (Terex Pegson, Model: QM020254T / QM021023) of larger capacity and consideration of its acceptability against Condition 3 pertaining to noise of planning permission RR/700/CM.

Future Site End-use Continuation of processing of construction and demolition waste in accordance with planning permission.

SITE INFORMATION

Site Address Land at Hole Farm, Westfield Lane, Westfield, East Sussex, TN35 4SA

CONCLUSIONS

A noise assessment in collaboration with the Planning Department of ESCC has been undertaken in

relation to the proposed operation of a replacement mobile crusher y for the processing of construction

and demolition waste materials at land at Hole Farm in Westfield, having regard to Condition 3

(pertaining to noise) of planning permission RR/700/CM.

The results of the assessment indicate that with the proposed noise control measures maintained in

place indefinitely, notably a local three sided ‘U’ shaped 5.0m high soil bund around the crusher,

together with dampening of the response of the collection hopper through stiffening of the steel casing,

the noise requirements of Condition 3 will be met.

To help present a balanced and complete picture of the nature of residual noise experienced at the

closest NSRs to the Site, the ‘real-time’ impact of source activity noise levels at the closest NSRs to the

Site were evaluated through simultaneous source and receiver noise measurement undertaken during

operation of the crusher installed as for normal usage and operated in a manner corresponding to

maximum sound generation representative of normal use. Receiver measurements were fully attended

with audio recording samples taken in order that exact details of all witnessed activities / noise sources

could be accurately correlated to the measured data.

Real-time attended measurements at Willows End and Sandhole Farm revealed noise from operation of

the proposed mobile crusher was immeasurable and inaudible (and therefore did not materially

contribution to the noise climate).

As witnessed and supported by measurement, noise associated with activities at Hole Farm were at the

threshold of measurability and audibility at 115 Westfield Lane. Concurrent source and receiver noise

level time histories shown to be largely independent of one another exhibiting no strong correlations

even for the highest measured source activities. Significant events, notably, the loading of material into

the collection hopper were found to be only occasionally and then barely and unobtrusively audible in

between lulls in other ‘masking’ environmental noises, e.g. traffic, wildlife. The rapid sound pressure

level rate of change of short-lived maxima events and acuity of human hearing governing factors in a

listener’s occasional recognition of source noise at 115 Westfield during lulls in background noise, not

the absolute sound pressure level.


Page 1

1. Introduction

Waterman Energy, Environment & Design Ltd (hereafter “Waterman”) have been appointed by Mr Robin

Bristow (hereafter “the Applicant”) to undertake a noise assessment in relation to the proposed operation

of a replacement mobile crusher at land at Hole Farm, Westfield Lane, Westfield, East Sussex, TN35 4SA

(hereafter referred to as the “Site”). The throughput limit of 10,000 tonnes per annum is to remain

unchanged.

This report assesses noise emissions from the proposed crusher and considers the acceptability of it

against Condition 3 (pertaining to noise) of the extant planning consent (Ref. No. RR/700/CM). A

combination of calculation and simultaneous source and receiver noise measurement was undertaken

during operation of the crusher installed as for normal usage and operated in a manner corresponding to

maximum sound generation representative of normal use to present a balanced and complete picture of

the nature of noise intrusion experienced at the closest noise-sensitive receptors (NSRs) to the Site.

A glossary of the acoustic terminology used in this report is presented in Appendix A.


Page 2

2. Site and Development Description

2.1 Site Description

The Site comprises of a parcel of land at Hole Farm, Westfield Lane, Westfield, East Sussex, at

approximate post code TN35 4SA and National Grid Reference (NGR) TQ 810 138.

The noise climate of the area is dominated by local road traffic passing along Westfield Lane.

Contributory noise from metal recycling and waste handling activities at H. Ripley and Co., bird song, the

rustling of leaves, passing aircraft and human activities in the area were also evident and influence the

noise climate to a degree.

The closest NSRs to the Site are residential in nature and are shown in Figure 1 and described in Table

1.

Table 1: Noise Sensitive Receptors

Assessment Location (Figure 2)

Description

NSR A 115 Westfield Lane approximately 100m from western site boundary

NSR B Willows End approximately 210m from western site boundary

NSR C Sandhole Farm approximately 100m from the north eastern site boundary

The location of the Site and orientation with respect to the nearest NSRs and the noise monitoring

locations used in this assessment are presented in Figure 1.

2.2 Development Description

Permitted process operations conducted on site include the recovery of up to a maximum of 10,000

imported tonnes per year of construction and demolition materials (e.g. brick / block / concrete / hardcore

/ stone) by means of:

sorting (including by means of manual and machine picking of targeted materials) of waste materials

into recoverable fractions and residual wastes;

crushing of brick / block / concrete / hardcore / stone; and

diverting recovered waste (including metal reinforcing bar recovered from crushing reinforced

concrete) to offsite re-processors.

The permitted hours of use are detailed below in Table 2 and are to remain unchanged.

Table 2: Summary of Permitted Hours of Use

Period Receipt, Loading and Dispatch of Materials Crushing

Monday to Friday 08:00 – 18:00 09:00 to 16:00

Saturday 08:00 - 13:00 No works

Sunday No works No works

Public and Bank olidays No works No works

2.3 Consultation

This investigation has been undertaken in collaboration with Jeremy Patterson, Principal Planning Officer,

at East Sussex County Council (ESCC) in order to ensure impartiality and agreement over the accuracy


Page 3

of assessment findings. Jeremy Patterson, Principal Planning Officer, of ESCC attended site on 12 July

2013 during typical crushing operations and witnessed first-hand ‘actual’ site activities and the ‘real’

impact of operations at the closest NSRs to the Site formally presented within this report.


Page 4

3. Assessment Criteria

3.1 Condition 3 of Planning Consent RR/700/CM

The significance of noise impacts depends upon a number of factors including the noise level, the nature

of the noise, the time at which the noise occurs, whether the noise is temporary or permanent, whether

the impact is from a new source, or whether it is a change to an existing source and the sensitivity of the

receptor. Ultimately, however, noise from operational plant and activities needs to comply with Condition

3 of the extant planning consent requiring:

‘The noise rating level emitted from the site shall at all times not exceed 43dB LAeq,1hour (free-field) when

measured in accordance with BS4142:19971 or equivalent at Noise Sensitive Receptor A (115 Westfield

Lane) shown in Figure 4 of the Addendum Noise Report dated August 2012.’

The target criterion of 43dBA is based on the lowest measured weekday and weekend background

(LA90,T) noise level obtained on a weekend at the nearest noise-sensitive receptors and therefore

represents a worst case scenario when noise impact can be considered greatest, thereby ensuring

maximum protection to the residential amenity of nearby sensitive receptors. In reality, during the

permitted operational crushing period of 09:00 to 16:00 hours Monday to Friday only, local environmental

noise levels would be higher (>5dB) than those reported and can be expected to provide beneficial

masking.

3.2 The Concept of Noise, Disturbance and Annoyance

To help provide greater clarity and context to this report, the concept of noise, disturbance and

annoyance are outlined below.

Noise is a pollutant. A dictionary definition of noise is “a sound, especially one that is loud or disturbing”.

Thus, noise is made up of sound and it is sound which is considered by the recipient as undesired or

unwanted, which is noise. What one person considers undesirable may to another be acceptable, with

noise related issues open to personal and subjective interpretation. However, noise per se is closely

linked with the ideas of disturbance and annoyance which in turn can be considered dynamic constantly

moving social ‘goal posts’ influenced by subjective factors including: situation; attitude; aspiration;,

affluence; familiarity; differential sensitivity etcetera.

In total there is a very complex multi-dimensional relationship between the various characteristics of

environmental noise and the effects it has on people. Excessive noise, though, has the capacity to

damage hearing (the most severe physiological effect), interrupt sleep, disrupt concentration, interfere

with communication in all its forms (conversation, telephone, television, radio) to simply annoy, which is a

phenomenon of 'mind and mood' and a subjective term in general for all negative feelings such as

dissatisfaction, displeasure or irritation. Consequently there may be annoyance but no actual disturbance

or nuisance.

Noise affects us all in one way or another, however, the sound level of the acoustic stimulus, its

psycho-acoustical sound characteristics, the time of its occurrence, its time course, its frequency

spectrum and its informational content modify the reaction. Most people would agree that some noise in

our modern society is inescapable, but would expect that noise should be mitigated whenever possible.

It should be stated that no single noise index (e.g. LAeq,T, LAFmax) producing an objective result can ever

give the whole picture, nevertheless there will always be a place for scientific measurements whenever

possible to reinforce subjective interpretations as considered in this commission.

1 British Standard (BS), 1997, BS4142:1997 ‘Method for Rating Industrial Noise Affecting Mixed Residential and Industrial Areas’.

British Standards Institute.


Page 5

4. Noise Survey & Assessment Results

4.1 Assessment of Operational Impacts

Due to there being no obvious source specific noise at the assessment location of 115 Westfield Lane

combined with interference from local noise sources, it was not possible to directly measure the specific

noise contribution from the proposed crusher. A combination of source measurement and calculation

was therefore used to assess compliance with Condition 3 of the planning consent.

4.2 Determination of Crusher Sound Power Level

Source noise measurements were undertaken at a set distance of 10m on all sides of the proposed Terex

Pegson mobile concrete crusher (Model: QM020254T / QM021023) installed as for normal usage and

operated in a manner corresponding to maximum sound generation representative of normal use to allow

determination of the operational sound power level of the crusher. The assessment was undertaken

having regard to the methodology outlined in BS EN ISO 3746:2010: ‘Acoustics – Determination of sound

power levels of noise sources using sound pressure – Survey method using an enveloping measurement

surface over a reflecting plane’.

As part of the proposal, the following controls have been implemented and will be retained indefinitely

(subject to planning permission) in seeking compliance with Condition 3 of the planning consent, so as

not to adversely prejudice the noise climate and amenity of local residents:

Local three sided ‘U’ shaped 5.0m high soil bund at 4.0m horizontal distance around the crusher; and

Dampening of the response of the collection hopper through stiffening of the steel casing.

In addition, as a matter of best practice and good neighbourliness, in order to ensure noise is mitigated

whenever possible, the following outline noise controls will be adopted as a matter of course:

Minimisation of material drop heights in to the collection hopper;

Plant to be properly maintained and operated in accordance with manufacturers’ recommendations;

Plant to be throttled down and/or switched off when not in use; and

No use of vehicle horns other than in an emergency.

Measurements were taken using a calibrated precision grade (Class 1) sound level meter. Full details of

the instrumentation used for the noise measurements, including calibration certificates are available on

request.

Weather conditions were generally ideal for the measurement of noise, it being dry with still air or only a

light east north east breeze (<5ms-1

).

The results of the noise measurements are outlined below in the Table 3, together with the calculated

operational sound power level of the mobile crusher.

Table 3: Measured Mobile Crusher Noise Emission Levels at 10m and 20m

Position Measured Noise Level at 10m (dB re 20 x 10

-6 Pa.)

Lw1

LAeq,5min LAFmax

North (rear) 70 81

118 East (side) 81 92

South (front) 77 87

West (side) 80 92

Notes:

Note 1 - conformal surface area sound power level determined based on field measurements taken at 10m.


Page 6

4.3 Predicted Noise Level at 115 Westfield Lane

The average measured noise level from the mobile crusher at 10 metres was used to predict the noise

level at the primary external amenity area of 115 Westfield Lane, taking account of distance attenuation

and screening afforded by the ‘U’ shaped bund. The assessment assumes a worst case scenario of the

crusher operating continuously at full capacity and that sound attenuation due to atmospheric absorption

is negligible. Table 4 presents the calculation details.

Table 4: Predicted Noise Level of Mobile Crusher at 115 Westfield Lane

Description Octave Band Centre Frequency (Hz) dB(Linear)

dBA 63 125 250 500 1k 2k 4k 8k

Measured Level at 10m from

Mobile Crusher, dB Leq,1hr 82.1 82.9 78.7 83.9 78.1 72.9 67.1 60.7 84

Screening Loss, dB1 -10.7 -13.1 -15.7 -18.6 -21.5 -25.0 -25.0 -25.0 -

Acoustic Feature Correction, dB2 0 0 0 0 0 0 0 0 -

Distance Loss (115m), dB -21.2 -21.2 -21.2 -21.2 -21.2 -21.2 -21.2 -21.2 -

Rating Level at Patio/Garden of

115 Westfield Lane Leq,1hr 50.2 48.6 41.8 44.0 35.4 26.7 20.9 14.5 43

Notes:

Note 1: Includes screening loss from onsite three sided ‘U’ shaped 5.0m high soil bund located 4.0m horizontal distance from the

crusher.

Note 2: As witnessed and supported by measurement at 115 Westfield Lane (see Figure 2, Section 4.4), source noise from

activities at Hole Farm are at the threshold of measurability and audibility. Significant events barely and only occasionally audible

in between lulls in other ‘masking’ environmental noises, e.g. traffic, wildlife. As such, a +5 dB acoustic feature penalty has not

been applied. However, should plant/events become obtrusive with plainly distinguishable features present then the plant noise

level should be adjusted (i.e. 5dB added to obtain the rating level).

From Table 4 above, it can be seen that a rating noise level of 43dB LAeq,1hour is predicted at the primary

external amenity area of 115 Westfield Lane. This is equal to the lowest measured background (LA90,T)

noise level of 43 dBLA90,5min and is therefore in compliance with Condition 3 of the planning consent and

the noise requirements of ESCC.

4.4 Simultaneous Source and Receiver Noise Levels

To help evaluate the ‘real-time’ impact of source activity noise levels at the closest noise-sensitive

receptors, noise measurements were taken simultaneously at source and receiver positions during

normal operation of the crusher and serving excavators.

The measurements were fully attended with audio recording samples taken in order that exact details of

all witnessed activities / noise sources could be accurately correlated to the measured data, enabling

accurate comparisons to be drawn between the measured noise levels at each of the positions. This

approach also enabled a subjective aural assessment of the characteristics of residual noise to be noted,

informing application of the +5dB acoustic feature, having regard to the dominance and audibility of

intruding noise.

All measurements were made with Rion NL-52 precision grade sound level meters, set-up to integrate

continuously over 1 second fast response time constant intervals to allow capture of individual discrete

noise events.

The noise measurement equipment was calibrated at the beginning and end of each series of

measurements using a Rion acoustic calibrator, which had itself been calibrated against a reference

system traceable to National and International Standards. No significant change (+/-0.1 dB) in the

calibration level was noted.


Page 7

For all the measurements the sound level meters were mounted on a tripod at a height of 1.5 metres from

the ground with the microphone positioned in free-field conditions.

A summary of the on-site (Source) and off-site (Receptor) measured noise levels in terms of the

LAeq,1second noise indices during operation of the crusher are displayed graphically in time-history format in

Figures 1 to 2. The graphs are annotated to provide clarity on the nature (i.e. type, timing, relative

frequency, duration) and absolute level of source and receiver activity noise levels associated with the

use of the mobile crusher.


Page 8

Willows End and Sandhole Farm

The daytime noise climate at Willows End and Sandhole Farm, approximately 210m and 160m distance

from the mobile crusher respectively, were characterised by local noise sources, notably, metal recycling

operations at H. Ripley and Co. and road traffic noise on Westfield Lane (the A28). Subjectively, noise

from operation of the crusher was inaudible at Sandhole Farm and Willows End, except for a single

individual discrete event discerned at Willows End of uncertain origin during a lull in background noise

from local sources (road traffic, birdsong).

Subjective aural assessment findings were found to be in-keeping with objective external assessment

results taken simultaneously at source and receiver locations, illustrated in Figure 1, which clearly

indicate that source activity noise associated with the crushing of inert construction and demolition waste

is immeasurable and does not contribute to the noise climate.

115 Westfield Lane

At 115 Westfield Lane, approximately 115m distance from the crusher, the daytime noise climate is

dominated by road traffic noise on Westfield Lane. As witnessed and supported by measurement, noise

associated with activities at Hole Farm were at the threshold of measurability and audibility. Review of

Figure 2 showing concurrent source and receiver noise level time histories to be largely independent of

one another exhibiting no strong correlations even for the highest measured source activities. Significant

events, notably, the loading of material into the collection hopper only occasionally and then barely and

unobtrusively audible in between lulls in other ‘masking’ environmental noises, e.g. traffic, wildlife. The

rapid sound pressure level rate of change of short-lived maxima events and acuity of human hearing

governing factors in a listener’s occasional recognition of source noise at 115 Westfield during lulls in

background noise, not the absolute sound pressure level.


Page 9

5. Conclusions

Waterman have been commissioned to undertake a noise assessment in relation to the proposed

operation of a replacement mobile crusher (Terex Pegson, Model: QM020254T / QM021023) of larger

capacity for the processing of inert construction and demolition materials at land at Hole Farm in

Westfield, having regard to Condition 3 pertaining to noise of planning permission RR/700/CM.

This investigation has been undertaken in collaboration with the Planning Department of ESCC with the

intention of agreeing the survey protocol and ensuring impartiality over the accuracy of reported

assessment findings. Jeremy Patterson, Principal Planning Officer, of ESCC attending site on 12 July

2013 and witnessing first-hand ‘actual’ site operations and the ‘real’ impact of site operations at the

closest NSRs to the Site formally presented within this report.

To help provide greater clarity and context to result findings presented, the underlying aims of Condition 3

have been considered, whilst the concept of noise, disturbance and annoyance have been outlined in

Section 3 of this report.

Due to there being no obvious source specific noise at the assessment location of 115 Westfield Lane

combined with interference from local noise sources, it was not possible to directly measure the specific

noise contribution from the proposed crusher as first intended. A combination of source measurement

and calculation was therefore used to assess compliance with Condition 3 of the planning consent

pertaining to noise (Ref. No. RR/700/CM). The results of the assessment indicate that with the proposed

noise control measures in place the noise requirements of Condition 3 will be met.

To help present a balanced and complete picture of the nature of residual noise experienced at the

closest NSRs to the Site, the ‘real-time’ impact of source activity noise levels at the closest NSRs to the

Site were evaluated through simultaneous source and receiver noise measurement undertaken during

operation of the crusher installed as for normal usage and operated in a manner corresponding to

maximum sound generation representative of normal use. Receiver measurements were fully attended

with audio recording samples taken in order that exact details of all witnessed activities / noise sources

could be accurately correlated to the measured data.

Real-time attended measurements at Willows End and Sandhole Farm revealed noise from operation of

the proposed mobile crusher to not contribute to the noise climate being immeasurable and inaudible,

except for a single individual discrete event discerned at Willows End of uncertain origin during a lull in

background noise from local sources (road traffic, birdsong).

As witnessed and supported by measurement, noise associated with activities at Hole Farm were at the

threshold of measurability and audibility at 115 Westfield Lane. Concurrent source and receiver noise

level time histories shown to be largely independent of one another exhibiting no strong correlations even

for the highest measured source activities. Significant events, notably, the loading of material into the

collection hopper were found to be only occasionally and then barely and unobtrusively audible in

between lulls in other ‘masking’ environmental noises, e.g. traffic, wildlife. The rapid sound pressure level

rate of change of short-lived maxima events and acuity of human hearing governing factors in a listener’s

occasional recognition of source noise at 115 Westfield during lulls in background noise, not the absolute

sound pressure level.


Figures

Figures

Figure 1: Location Plan of the Site, Receptor and Survey Positions


Appendices

Appendices


Appendices

Appendix A Glossary of Acoustic Terminology

Ambient sound The totally encompassing sound in a given situation at a given time, usually composed of

sound from all sources near and far.

Assessment

period The period in a day over which assessments are made.

A-weighting A frequency weighting applied to measured or predicted sounds levels in order to compensate

for the non-linearity of human hearing.

Background

noise Background noise is the term used to describe the noise measured in the absence of the noise

under investigation. It is described as the average of the minimum noise levels measured on a

sound level meter and is measured statistically as the A-weighted noise level exceeded for

ninety percent of a sample period. This is represented as the L90 noise level (see below).

Broadband Containing the full range of frequencies.

Decibel [dB] The level of noise is measured objectively using a Sound Level Meter. This instrument has been specifically developed to mimic the operation of the human ear. The human ear responds to minute pressure variations in the air. These pressure variations can be likened to the ripples on the surface of water but of course cannot be seen. The pressure variations in the air cause the eardrum to vibrate and this is heard as sound in the brain. The stronger the pressure variations, the louder the sound is heard.

The range of pressure variations associated with everyday living may span over a range of a million to one. On the top range may be the sound of a jet engine and on the bottom of the range may be the sound of a pin dropping.

Instead of expressing pressure in units ranging from a million to one, it is found convenient to condense this range to a scale 0 to 120 and give it the units of decibels. The following are examples of the decibel readings of every day sounds;

Four engine jet aircraft at 100m 120 dB

Riveting of steel plate at 10m 105 dB

Pneumatic drill at 10m 90 dB

Circular wood saw at 10m 80 dB

Heavy road traffic at 10m 75 dB

Telephone bell at 10m 65 dB

Male speech, average at 10m 50 dB

Whisper at 10m 25 dB

Threshold of hearing, 1,000 Hz 0 dB

Free Field Free field noise levels are measured or predicted such that there is no contribution made up of

reflections from sound reflecting objects (e.g. buildings),usually taken to mean at least 3.5m

away.

dB(A):

A-weighted

decibels

The ear is not as effective in hearing low frequency sounds as it is hearing high frequency

sounds. That is, low frequency sounds of the same dB level are not heard as loud as high

frequency sounds. The sound level meter replicates the human response of the ear by using

an electronic filter which is called the ‘A’ filter. A sound level measured with this filter switched

on is denoted as dB(A). Practically all noise is measured using the A filter. The sound

pressure level in dB(A) gives a close indication of the subjective loudness of the noise.

Façade Noise

Level

A noise level measured or predicted at the façade of a building, typically at a distance of 1m,

containing a contribution made up of reflections from the façade itself (+3 dB).

Noise Level Indices

Noise levels usually fluctuate over time, so it is often necessary to consider an average or statistical noise level. This can be done in several ways, so a number of different noise indices have been defined, according to how the averaging or statistics are carried out.

Leq A noise level index called the equivalent continuous noise level over a specified period of time,


Appendices

T. This is the level of a notional steady sound that would contain the same amount of sound

energy as the actual, possibly fluctuating, sound that was recorded.

L10 The sound pressure level that is exceeded for 10% of the time for which the given sound is

measured. The L10 can be considered to be the “average maximum” noise level and is

generally used to describe road traffic noise.

L90 The level of noise exceeded for 90% of the measurement time interval, T. The L90 can be

considered to be the “average minimum” noise level and is often used to describe the

background noise.

Lmax The maximum noise level over a specified period of time, T, and unless described otherwise, it

is measured using the ‘fast’ sound level meter response. The LAFmax is sometimes used for the

assessment of occasional loud noises, which may have little effect on the overall LAeq noise

level but will still affect the noise environment.

Rating Noise Level (LAr,Tr)

The equivalent continuous A-weighted sound pressure level during a specified time interval, plus specified adjustments for tonal character and impulsiveness of sound.

Loudness A rise of 10 dB in sound level corresponds approximately to a doubling of subjective loudness. That is, a sound of 85 dB is twice as loud as a sound of 75 dB which is twice as loud as a sound of 65 dB and so on. That is, the sound of 85 dB is 400% times the loudness of a sound of 65 dB.

Noise Sound which a listener does not wish to hear.

Sound A fluctuation of air pressure which is propagated as a wave through air.

Sound level meter

An instrument consisting of a microphone, amplifier and indicating device, having a declared performance and designed to measure sound pressure levels.

Specific Noise Level

The monitored/calculated noise level as a result of a noise source excluding the impacts of any extraneous noise sources.


Appendices

hole farm, westfield lane, westfield, tn35 4sa

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