masking sari

Audiometric Masking

Febryanti P SariSupervisor : Dr. Yussy Afriani Dewi,dr., M.Kes.,

SpTHT-KL(K).,FICS

Department of Otorhinolaryngology Head & Neck SurgeryFaculty of Medicine Universitas Padjadjaran

RS Hasan Sadikin Bandung

2016

04/27/2023 2

Audiometry (from Latin: audīre, "to hear" and metria, “to measure") is a branch of Audiology and the science of measuring hearing acuity for variations in sound intensity and pitch and for tonal purity, involving thresholds and differing frequencies.

audiometric tests determine a subject's hearing levels with the help of an audiometer

Patrick J. Willems (2004). Genetic hearing loss. CRC Press. pp. 34–. ISBN 978-0-8247-4309-3. Retrieved23 June 2011.

https://en.wikipedia.org/wiki/Latin_language

https://en.wikipedia.org/wiki/Hearing_(sense)

https://en.wikipedia.org/wiki/Measurement

https://en.wikipedia.org/wiki/Audiology

https://en.wikipedia.org/wiki/Equal-loudness_contour

https://en.wikipedia.org/wiki/Audiometer

http://books.google.com/books?id=Na5q8f_NW4MC&pg=PA34

https://en.wikipedia.org/wiki/International_Standard_Book_Number

https://en.wikipedia.org/wiki/Special:BookSources/978-0-8247-4309-3

AUDIOGRAM

Masked Air

Definition The process by which the threshold of

hearing for one sound is raised by the presence of another (masking) sound and the amount by which threshold of hearing for one sound is raised by the presence of another (masking) sound expressed in decibels

Audiology: Diagnosis. Edited by Roeser, Valente, and Hosford-Dunn. Thieme Medical Publishers,Inc., New York.2000

Why do we mask? To prevent the non-test ear (NTE) from

participating in the test (cross-hearing) to make sure that when we are testing the

right ear, that we are getting the true threshold of the test ear (TE) and that the NTE is not helping out

This is necessary because of BONE CONDUCTION!› Our ears are housed in a bony skull, which

vibrates BOTH cochleae when sound is present at a certain level


04/27/2023 6

WHY? Cross Hearing!

Key Concept=Interaural attenuation! The amount of sound required to bridge across the head and stimulate the opposite cochlea by BC.

Unmasked thresholds trace out a “shadow curve” displaced from the non-test ear by the size of IA.


04/27/2023 8

Interaural Attenuation Interaural attenuation (IA) is the

amount of sound that is attenuated/reduced when crossing from one ear to the other

The IA varies:› Depending on the frequency› From patient-to-patient (skull thickness)› Depending on the transducer used

(phones, inserts, bone)

Interaural Attenuation value based on frequency and type of transducer (Stach)

10

Frrequency

Supra-aural (TDH 49)

Insertphone (ER-3A)

Vibrator BC

(Hz) (dB) (dB) (dB) 250 40 75 500 40 75 0 1000 40 60 0 2000 45 55 0 4000 50 65 0 8000 50 65

04/27/2023 11

IA minimum by Goldstein and Newman

IA of Air Conduction - Headphones

The minimum IA of headphones is 40 dB HL

If we present 80 dB to the test ear, 40 dB of that sound is reaching the cochlea of the non-test ear

Image from: wikipedia.org

IA of Air Conduction - Inserts The minimum IA of inserts is 70 dB HL If we present 80 dB to the test ear, 10 dB of that

sound is reaching the cochlea of the non-test ear› You are less likely to mask for air-conduction

testing when you use inserts

Image adapted from: wikipedia.org

IA of Bone Conduction

Image from: wikipedia.org

The minimum IA of bone conduction is 0 dB HL

If we present 30 dB to the test ear, 30 dB of that sound is reaching the cochlea of the non-test earYou must mask for bone-

conduction testing in conductive losses and asymmetrical losses

When to Mask-Air Conduction

Headphones: when there is a 40 dB or more difference between the air conduction threshold of the test ear and the bone conduction threshold of the non-test ear.

Inserts: when there is a 70 dB or more difference between the air conduction threshold of the test ear and the bone conduction threshold of the non-test ear.


When to Mask - Bone Conduction

When there is a 10 dB or more difference between the air conduction threshold of the test ear and the bone conduction threshold of the same ear › aka: Mask for BC when there is an air-bone

gap


04/27/2023 17

Type of masking noises Effectiveness and efficiency of masking

critical bandwith signal to be masked and type of masking noise used

White noise Narrow band noise speech noise


04/27/2023 18

TYPES OF MASKING NOISES

white noise or broad bandrandom energy distribution (the average is almost the same at all frequencies) are analogous to the distribution of light white color. Because spectrum is broad and flat, WN have limitations for masking pure tones


04/27/2023 19

TYPES OF MASKING NOISES

Narrow band noise / NBN The most efficient is to produce a shift in the

hearing threshold of the greatest intensity is the smallest sound masking

The results of the research of the most effective masking is around the frequency of the sound in masking

NBN intensity is lower than WN NBN can produce a shift in the threshold

without causing disruption due to masking intensity is too hard


04/27/2023 20

Effective masking level The amount of intensity noise that

should be given to prevent cross hearing

Minimum masking Maximum masking Over masking

Undermasking Not using enough noise in the non-test

ear The obtained threshold is really the

response of the non-test ear


Overmasking Using too much noise The obtained threshold is exaggerated

when the masker crosses the head and shifts the threshold of the test ear.

Traditionally, we use the plateau method to ensure that we have obtained a true threshold and are not undermasking or overmasking.


04/27/2023 23

PROBLEM IN MASKING

Central masking the increase in the threshold of hearing ear

being tested at the time of masking test starts (not yet achieve effective masking)

central masking between 5 —15 dB (usually around 5 dB)

oclussion effect Raising the threshold of hearing in the

closed ear due to the occlusion effect Commonly bone conduction with masking


04/27/2023 24

TRANSDUSER TYPES

Headphone / earphone Insertphone vibrator

04/27/2023 25

MASKING METHOD

Plateau method

formula method

step masking method

04/27/2023 26

PLATEAU (HOOD) METHODWidely used in the United KingdomLess desirable because the long test timeIt is recommended if the minimum and maximum masking area is very narrowProvide sound masking intensity increased gradually until it reaches a plateau which indicates that the threshold is actually in the ear being tested has been reached


04/27/2023 27

PLATEAU METHOD

Finding the threshold of the ear being tested (without masking)

Then the masking noise of 10 dB SL give to the ear not being tested and the hearing threshold test is repeated

Each time the masking sound intensity is raised 10 dB, the ear hearing threshold test is repeated


04/27/2023 28

PLATEAU METHOD

During the masking intensity is still under masking, any increase in the intensity of 10 dB will shift the hearing threshold of 10 dB

At a certain intensity, the increase in 10dB masking is no longer shifting threshold

Two increases masking noise by 10 dB, no longer shifting threshold reach plateau

Effective masking has been reached


04/27/2023 29

FORMULA METHOD

Air conduction Masking minimum (Mmin) = AC

threshold in TE –IA + A-B gap in NTE

Masking maximal (Mmax) = threshold BC in TE + IA


04/27/2023 30

FORMULA METHOD

Bone conduction Masking minimum (Mmin) = BC TE +

A-B gap NTE Masking maximum (Mmax) = BC TE +

IA note: Mmaks < UCL


04/27/2023 31

INITIAL INTENSITY MASKING (Sataloff)

Avoid under masking Easing achieve effective masking


04/27/2023 32

MASKING INITIAL INTENSITY (Sataloff)

Air conduction tests effective initial intensity is the intensity of

the initial masking as a guide at the start of the hearing threshold shift in the ear being tested

Sataloff performed on the intensity of the air conduction threshold of the ear not being tested + 30 dB


04/27/2023 33

Condition need masking for AC AS

04/27/2023 34

MASKING INITIAL INTENSITY (Sataloff)

Bone conduction test Bone conduction starts at the air conduction

threshold of the non test ear + 20 dB If the masking threshold ear in normal or

sensorineural deafness, should be added to 15dB at 250-500hz,and 10dB at 1000 Hz, which is the correction factor occlusion effect on the closed ear headphones

Above 1000 Hz occlusion effect is very minimal Conductive deafness not need the added value

occlusion effectAudiology: Diagnosis. Edited by Roeser, Valente, and Hosford-Dunn. Thieme Medical Publishers,Inc., New York.2000

04/27/2023 35

>

>

04/27/2023 36

STEP MASKING method(Katz dan Lezynsky)

Faster than methods plateau The increase in the intensity of masking

methods plateau only 5-10 dB each time, step masking using greater intensity =

20 dB Masking begins with providing EML

(Effective Masking Level) of 30 dB SL (Sensation Level)


04/27/2023 37

METODE STEP MASKING (Katz dan Lezynsky)

If the masking threshold after administration shifted by 15 dB or more required additional masking (subsequent masking / submask) of 20 dB

If the administration of the initial masking 30 dB SL EML no threshold shift or just a 5-10 dB, the likelihood is that the actual threshold (no cross-over hearing) so it does not need to be supplemented submask


04/27/2023 38

STEP MASKING METHOD (Katz dan Lezynsky)

CRITERIA AFTER INITIAL MASKING QUOTE FROM Abiratno.2005Threshold shifting with EML 30dBSL

need/not submask

0-10 dB No need15 dB possibly no need20 dB Possibly need to25 dB Need to

04/27/2023 39

STEP MASKING METHOD(Katz dan Lezynsky)

If the threshold in the ear being tested eased after the initial masking (30 dB SL EML)

The number of shifts in the ear threshold test showed indications of whether or not an additional masking / submask

If after submask summed (20 db above masking initial EML), an indication of the need to shift the threshold / absence of additional submask


04/27/2023 40

METODE STEP MASKING (Katz dan Lezynsky) Criteria after giving subsequent masking by Abiratno.2005

Threshold shifting with EML 20dBSL

Need/not submask

0-10 dB No need15 dB Possibly no need20 dB Possibly need> 20dB Need to

Masking for Speech Reception Threshold

Just like masking for puretones› Determine the need for masking and use

plateau method to determine effectively masked threshold for speech

› Minimum IA 45dB› Initial level masking 30dB› Subsequent mask is 20dB


04/27/2023 42

Masking for word recognition score(WRS)

Wrs doesn’t count hearing threshold,only using one level intensity

Using widely spectrum noise masking Level masking of the non test ear 30dB


04/27/2023 43

conclusion Masking may be necessary if one normal

ear and one ear of a hearing loss, or if there is an asymmetrical hearing threshold

Inspection begins frequency 1000 Hz The purpose masking to determine the

actual threshold of the ear suspected of having hearing problems and avoid the tested crossings from ear to ear not being tested (cross hearing)

04/27/2023 44

Given the time needed to carry out the masking procedure, then we need to understand a clear indication when required masking and masking effective intensity for each frequency being tested

If we doubt the diagnosis of hearing, whether conductive hearing loss (CHL), nerve deafness (Sensorineural hearing loss) or deafness mixture (SFM), absolutely necessary masking

04/27/2023 45

With audiometric we can distinguish or compare hearing threshold between conduction and bone conduction

Masking air conduction is done when there is a difference between AC and BC on both ears ≥ IA and bone conduction masking done in case A- B gap ≥10 dB

For masking procedure, in the field of audiology known three methods, namely methods plateau, method formula and step masking method

04/27/2023 46

Thank you

04/27/2023 47

Contoh penggunaan formula untuk menilai masking minimum dan maksimum

Telinga kanan: yang sedang dites Telinga kiri : gangguan konduktif ringan

dengan A-B gap : 30 dB (dikutip dati Hodgson 1980, Handbook of Clinical Audiology)

04/27/2023 48

Contoh kasus: Evaluasi pendengaran dengan

menggunakan metode step masking Kasus dengan gangguan pendengaran

unilateral kiri. Telinga kanan: Normal (AC dan BC rata-rata 10 dBHL). Telinga kiri : ambang AC tanpa masking rata-rata 55 dBHL tertera pada tabel 3.10

04/27/2023 49

04/27/2023 50

04/27/2023 51

METODE FORMULA

Formula Masking untuk tes hantaran udara

Mmin = At – 40 + (Am – Bm) Mmaks = Bt + 40 dengan catatan Mmaks

kurang dari UCL (uncomfortable loudness level)

NB: Nilai IA minimum untuk semua frekuensi yang dipakai dalam metode formula : 40 dB

04/27/2023 52

Berdasarkan pada panduan besar IA minimum untuk hantaran udara, semua frekuensi perlu di masking kecuali 4000 Hz dan 8000 Hz (besar IA lebih kecil dari IA minimum pada masing-masing frekuensi)

masking sari

Documents