hearing evaluation is important to assess type of deafnes so that proper treatment can be suggested to the patients.This helps to predict the efficacy of hearing aid also to judge which ear needs to be fitted with the hearng aid

1. Audiometry: Hearing Evaluation
Dr Shrikant Phatak
Head of ENT Department
Choithram Hospital & Research Center
Indore

2. Hearing Evaluation
• Normal human ear can hear frequencies
• 20–20,000 Hz but in routine audiometric
• testing only 125–8000 Hz are evaluated.
• Speech frequencies. 500, 1000 and 2000 Hz
are involved in day to day speech.
• Consonants consist of high frequency sounds

3. Hearing Evaluation
• A rough guide of intensities in day to day life
• Whisper = 30 dB
• Normal conversation = 60 dB
• Shout = 90 dB
• Discomfort of the ear = 120 dB
• Pain in the ear = 130 dB
• Loudness. It is the subjective sensation produced
by intensity.
• More the intensity of sound, greater the loudness

4. Hearing Evaluation: Rinne Test
To test air conduction (AC) a
vibrating fork is
placed vertically in line with
the meatus, about 2 cm
away from the opening of
external auditory canal.
• A vibrating tuning fork is
placed on the patient’s
mastoid and when he
stops hearing to test Bone
Conduction(BC)

5. Hearing Evaluation: Tuning Fork Tests
• 256 Hz,512 Hz ,1024 Hz Tuning Forks are used
• Rinne Test +ve AC better than BC
• Rinne -ve BC is better than AC
• Weber Test. Central in Normal /SN hearing Loss
• Weber is lateralized to worst ear in Conductive deafness.
• Weber is lateralized to better ear in SN deafness.
• A false –ve Rinne Weber is lateralized to the normal/better
ear .

6. Audiogram
Weber is Laterised to the more deaf ear in conductive
deafness in unilateral or Asymmetric Bilateral

7. Hearing Evaluation
• • A Rinne test equal or negative for 256 Hz but
positive for512 Hz indicates air-bone gap of
20–30 dB
• • A Rinne test negative for 256 and 512 Hz but
positive for1024 Hz indicates air-bone gap of
30–45 dB
• • A Rinne negative for all the three tuning
forks of 256, 512and 1024 Hz indicates air-
bone gap of 45–60 dB

8. Audiometry
• Audiometry consists of tests of function of the
hearing mechanism.
• Middle ear function,
• Cochlear function,
• Speech discrimination ability (central
integration).

9. Hearing Evaluation
• Audiometric zero is the mean value of minimal
audible intensity in a group of normally
hearing healthy young adults.

10. Hearing Evaluation
• Frequencies tested are 250 Hz,500Hz,1000Hz
• 2000Hz,4000Hz,6000Hz,8000Hz
• Interoctaves 750Hz ,15000Hz,3000Hz,6000Hz.
• Interoctaves thresholds are tested when two
consecutive frequency threshold shift is more
than 20dB.

11. Hearing Evaluation
• Threshold assessment is done by descending
technique
• The intensity at which the response is correct
for 50% of the times is the threshold.
• Bone Conduction testing 250Hz –4000Hz.
• Masking needed while testing Air Conduction
in Unilateral Deafness and in Bone Conduction
in Conductive Deafness

12. Audiogram
Thresholds up to 20dB
indicate Normal hearing
Thresholds 20—
40dBMildHearing Loss
Thresholds between 40—
60 dB Moderate Hearing
Loss
Thresholds60—
80dBSevere Hearing Loss
Thresholds 80dB onwards
Profound Hearing Loss

13. Hearing Evaluation
• Special tests differentiate Cochlear & Retro cochlear
Hearing Loss
• Tone Decay seen in Retro cochlear pathologies up to the
range of 25dB for all the tested frequencies Acoustic
Neuroma
• SISI Test
• ABLB test done in Asymmetric SN Loss of more than
30dB .Positive ABLB indicates recruitment
• Most Comfortable level
• Loudness Discomfort Level is reduced in recruiting Ears

14. Speech Audiometry
• SRT Speech Reception Threshold
• Minimum intensity at which 50% of spondee
(disyllable with equal stress) words are
correctly identified.
• SDS (Speech Discrimination Score) speech
discrimination is a measure of how well you
understand what you hear when speech is
loud enough to hear comfortably.

15. Speech Discrimination
• This is tested by using monosyllables 20 dB
above SRT. This is expressed in %.
• In Retro cochlear deafness (Acoustic
Neuroma) SDS scores are poor.
• Cochlear deafness SDS scores are better.
• SDS is a guide to which side hearing aid is to
be fitted.

16. Speech Discrimination
• The results of this test are recorded as a “%”
on your hearing test form. The number is the
per cent of words you repeated back
correctly. Normal speech discrimination is
100%, mild 85-95%, moderate 70-80%, poor
60-70%, very poor 40-50%, below 35% very
severely impaired.
• Greater the SDS% Happier is the patient with
the hearing aid

17. Audiometry
• Since both the ears
have Discrimination
score 90%
• Hearing aid will
benefit the patient in
either of the ears

18. Audiometry
Patient can complain of
diminished hearing on
Right side left ear being
better and SDS is more on
left side first give the aid
to left ear once patient is
used to hearing aid then
the other ear can be
fitted with a proper aid

19. Audiometry
Since the left ear has
SDS of 70% and
Right ear SDS is 50%
patient will be
benefitted by
hearing aid on Left
side only

20. Audiometry
In this case as
SDS is very poor
on left side
patient will be
benefitted by
using hearing
aid on Right ear

21. Audiometry
Thank You

22. Disclaimer
• The information contained in the presentation is based on the
personal experience and cases collected at Choithram Hospital
Indore over the last 20 years.
• It is intended for the use of Medical students ENT post graduates.
• The views expressed are purely on personal opinion. viewers can
make their own opinion. For any confusion please contact sole
author.
• Everybody is allowed to copy or download the material best suited
to him. I am not responsible for any controversies arising out of the
presentation.
• For any suggestions or corrections you may please contact
phatak_shrikant@yahoo.in