It is a useful tool to assess the middle ear function.

1. Clinical Utility of Impedance Audiometry
Audiometry Interpretation
Dr Shrikant Phatak
Consultant & Head of ENT Deptt
Choithram Hospital Indore

2. Clinical Utility of Impedance Audiometry
• A valuable objective test that
provides information about
the state of Middle ear.
• A tone delivered into the ear is
partly absorbed by sound
conducting apparatus & partly
reflected by the tympanic
membrane.
• There is maximum absorption
of sound when the pressure
on the either sides of
tympanic membrane is equal.
• Sound reflected by tympanic
membrane by varying air
pressure in the external canal.

3. Clinical Utility of Impedance Audiometry
Parameters which assess
middle ear function are
 Static compliance
 External canal volume
 Middle ear pressure
 Acoustic reflexes
 Eustachian tube
Function

4. Clinical Utility of Impedance Audiometry
A Normal Middle ear function ,B Middle ear effusion,
C Negative Middle ear pressure D Hypermobile TM or
Ossicular discontinuity , As ossicular fixation

5. Clinical Utility of Impedance Audiometry
Mixed Deafness PTA
Grommet insertion corrects
middle ear component

6. Clinical Utility of Impedance Audiometry
B curve Left

7. Clinical Utility of Impedance Audiometry
Low Static Compliance indicates Ossicular fixation
which can be Otosclerosis ,Congenital Ossicular
fixation
• Right 0.17ml thick foot plate than left0.28ml
although PTA can be symmetrical in Both the ears

8. Clinical Utility of Impedance Audiometry
In Otosclerosis this indicates even if PTA
thresholds are symmetrical Left foot plate is thin

9. Clinical Utility of Impedance Audiometry
PTA in Larger negative
pressures
More than --100 dapa need
Grommets

10. Clinical Utility of Impedance Audiometry
PTA thresholds in mild negative
pressure
Such patients respond to medical
treatment

11. Clinical Utility of Impedance Audiometry
Middle Ear effusion with Air Fluid
Level Needs Grommet Insertion

12. Clinical Utility of Impedance Audiometry
• A sound intensity 70 dB above the hearing threshold is
presented to the ear the Stapedius muscle contracts and
alters the impedance values . This useful to diagnose
• Malingering
• Detect roughly Pure tone thresholds in small children &
infants.
• To localize the site of lesion in cases of Facial Paralysis.
• Indirectly indicates presence of Recruitment.
• Presence of Reflex Decay indicates Retro cochlear pathology
like Acoustic Neuroma

13. Clinical Utility of Impedance Audiometry
• 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& Pediatric post
graduates and the students of Audiology
• 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

14. Clinical Utility of Impedance Audiometry
• Thank you