This document discusses acoustic immittance testing, specifically tympanometry. It begins by defining key terms like acoustic immittance, impedance, and admittance. It then describes the process of tympanometry testing including instrumentation, measurement of static compliance, and interpretation of results. Common tympanogram shapes are classified according to systems like Jerger-Liden and Feldman. The document also notes factors that can affect tympanometry and limitations of the test. In summary, tympanometry is a quick, non-invasive test that assesses middle ear function by measuring acoustic immittance at varying ear canal pressures.

1. Dr. Mona Hassan Selim
Prof. of Audiology
Cairo University
Dr. Mona Selim

2. Acoustic immittancemetry
• Acoustic immittance is a general term
used to refer to an acoustic energy
transfer regardless of the manner in
which it is measured.
Dr. Mona Selim

3. Acoustic impedance (ZA):
• The middle ear opposes the transfer of
energy to some extent. This opposition is
termed acoustic impedance(in ohms).
Acoustic admittance (YA)
• The resulting energy flow or transfer of air
pressure changes at the eardrum into
movements within the cochlear fluid is
termed acoustic admittance(in mhos).
Dr. Mona Selim

4. Tympanometry
I) Definition: Dynamic measure of the acoustic
immittance in the ext. ear canal, as a function
of ear canal air pressure change.
II) Principle: Air pressure is varied +ve and -ve
relative to ambient or atmospheric pressure
and is measured by detecting reflected SPL
from T.M.
Dr. Mona Selim

5. III) Instrumentation:
a) Preliminary steps:
* Otoscopic examination.
* Instructions to patient.
* Achieving air tight seal.
b) Equipment for M.E immittance measurements:
Dr. Mona Selim

6. 1. Loudspeaker: emits puretone (incident wave).
2. Microphone: picks sound in the ear canal (both
incident wave +reflected wave from eardrum).
3. Air pump: creates +ve or -ve pressure (1dapa=
1.02 mmH2O).
4. A.R activator source (ipsilateral).
Dr. Mona Selim

7. IV) Measurement of static compliance of ME:
1. Ensure clean ear canal.
2. Ear tip is pressed into canal.
3. ↑ pressure with air pump until air tight seal
is obtained.
4. ↑ pressure  200 daPa (C1).
C1 = equivalent volume in cm3.
= compliance of the outer ear.
Dr. Mona Selim

8. 5. ↓ pressure gradually until ear drum achieves
max. compliance (pressure on both sides of
drum is equal). (C2).
C2= Compliance of outer + middle ear.
Cx = Static compliance of M.E (Ytm)
Cx = C2-C1 Normally: 0.28-2.5 cm3
Dr. Mona Selim

9. • A 1 cm3 volume of air at sea level under
reference conditions, has an acoustic
admittance of 1 acoustic mmho for a 226-Hz
probe tone.
1 cm3 ~ 1 mmho
Dr. Mona Selim

10. Ytm= Ya-Vea
.Ya= total admittance Ytm= admitt. at t.m
Vea= vol. of ext. canal
Dr. Mona Selim

11. A compensated (Baseline) tympanogram
The contribution of the ext. canal has been removed
Dr. Mona Selim

12. Physical volume test (PVT):
Equivalent E.C. volume (Vec).
• An interesting application of Vec measure
has been suggested to identify a perforation
of the ear drum or a patent PE tube.
• Both conditions will lead to an ↑ in C1
volume than normal:
• Vec adults ~ 0.6-1.5 cm3
children ~ 0.4-0.9 cm3
Dr. Mona Selim

13. N.B.:
• An ↑ in volume between 2 ears
> 0.4cm3 children
> 0.87cm3 adults
is suggestive of a perforation.
• An abnormally small C1 volume
– Impacted cerumen.
– Probe impacted against wall.
• Normal C1 volume + type B tympan.
– ME effusion.
– Neoplasm.
– Lateral ossicular fixation.
Dr. Mona Selim

14. Pinhole Perforation
• Vec = within normal range.
• Ytm = can be normal.
• However, a unique tympanometric pattern
can be detected:
Dr. Mona Selim

15. Dr. Mona Selim

16. Interpretation of flat tymp. using Vec
a = Vec normal  M.E effusion.
b = Vec small  improper placement or cerumen.
c = Vec large  perforation or patent tube
Dr. Mona Selim

17. • Large Vec  suggests perforation.
• Normal Vec  DOES NOT exclude the
existence of a perforation. There may be
associated:
– ME effusion.
– Cholesteatoma.
– Obliteration of the mastoid air cells.
Dr. Mona Selim

18. Clinical uses of tympanograms:
1. Determination of TPP.
2. Amplitude of tympanogram  admittance at T.M
(Peak compensated static acoustic admittance)
(peak Ytm).
3. Vec.
4. Tympanometric shape and width: variety of
patterns associated with different pathologies.
Dr. Mona Selim

19. VI) Classification of tympanometric shapes:
A) Jerger-Liden classification
• Categorized according to shape and
tympanometric peak pressure.
Type (A)
• It is the normal tympanogram.
• The peak is at or near zero pressure (dapa).
• It reflects normal air filled middle ear.
• -100 +50 dapa.
Dr. Mona Selim

20. Dr. Mona Selim

21. Type AD:
• It is a tympanogram with abnormally high peak > 2.5
mmhos.
• Found in cases of T.M and ossicular abnormalities (e.g
disruption).
Type AS:
• It is a tympanogram with reduced amplitude < 0.28
mmhos.
• Found in:
– Ossicular fixation.
– Some forms of otitis media (adhesive, serous).
– Tympanosclerosis. Dr. Mona Selim

22. Dr. Mona Selim

23. Type B
• Flat.
• Represents non-mobile T.M.
• Occurs in the presence of ME effusion.
• Or space occupying lesion.
Dr. Mona Selim

24. It can be seen with large C1 volume in:
• T.M perforation.
• Patent PE tube.
It can be seen with abnormal small C1 volume:
• Impacted cerumen.
• Improperly placed immittance probe.
Dr. Mona Selim

25. Type C
• -ve peak pressure
• Indicating -ve M.E pressure with intact
mobile T.M with poor ET function.
Type D
Shows sharp notching characteristic of:
• Scarred eardrums.
• Normal hypermobile T.M.
Dr. Mona Selim

26. Type E
• Brood, smooth notching
• most commonly found in cases of
partial or complete ossicular
discontinuity.
Dr. Mona Selim

27. Dr. Mona Selim

28. Tympanogram Width (TW)
• Used to quantify the tympanogram shape in
the vicinity of the peak and is sometimes
called the tympanogram gradient.
• Measured as the WIDTH in pressure (daPa) of
the tympanogram at half of the height from
the peak to the tail.
Dr. Mona Selim

29. • Normally ~ 100 daPa
∀ ↑ TW  ME effusion (TW > 275 daPa).
∀ ↓ TW  TM abnormalities (scarring,
tympanosclerosis), ossicular fixation.
Dr. Mona Selim

30. Feldman Classification
Based on analysis of:
• Tympan. Peak pressure.
• Amplitude.
• Shape.
1) Tympanometric peak pressure
Normal -ve +ve Flat
Dr. Mona Selim

31. Pathologies with –ve M.E pressure:
• Serous otitis media.
• E.T malfunction.
Pathologies with +ve M.E pressure:
• Early acute O.M.
• Physiological conditions.
Valsalva/sneezing/ coughing.
Dr. Mona Selim

32. Pathologies with normal pressure:
• Ossicular fixation.
• Ossicular discontinuity.
• Adhesive O.M.
• Scarring T.M.
Absent pressure peak (flat):
• Adhesive O.M.
• Secretory O.M.
• Tiny perforation.
• Seal against wall.
Dr. Mona Selim

33. 2) Amplitude:
• It is a function of the compliance of the
system.
Increased amplitude:
• Monomeric T.M (Hypermobile).
• Ossicular discontinuity.
Dr. Mona Selim

34. Decreased amplitude:
• Ossicular fixation:
– Congenital.
– Otosclerosis.
– Paget disease.
• Adhesive O.M.
• Cholesteatoma, polyps, Granuloma.
• Glomus tumors.
• Fluids, mass.
Normal amplitude:
• Eust. Tube malfunction.
• Early acute O.M.
Dr. Mona Selim

35. 3) Shape Slope
Smoothness
• Tymp. shape is related to amount and not
viscosity of M.E effusion.
• Presence of a peak  presence of air in the
M.E. with or without effusion (good
prognosis in O.M).
Dr. Mona Selim

36. SLOPE
Flattened slope:
• Secretory O.M.
• Ossicular fixation.
• Tumors of the M.E.
Peaked or ↑ slope:
• Ossicular discontinuity
• TM abnormalities.
Dr. Mona Selim

37. Notched:
• Monomeric drum.
N.B.: Pathologies altering tympanometric
smoothness.
• Scarring of T.M.
• Ossicular discontinuity.
• Vascular tumours.
• Patulous E.T.
• Adhesive O.M. Dr. Mona Selim

38. VII) Procedural variables affecting tympan.
amplitude and shape.
1) Rate of ear canal pressure change
Amplitude
∀ ↑ in amplitude when pressure rate was increased
from 200 dapa/sec  400 dapa/sec.
Shape
• More frequent notching at high rates of pressure
change (esp. high frequency tympanograms).
Dr. Mona Selim

39. 2) Direction of ear canal pressure change
• In normal ears: Mean acoustic admittance is greater
for increasing (-ve  +ve) than for decreasing (+ve
 -ve) press. change.
• Not consistent across individuals.
• Higher incidence of notched tympanograms in
increasing vs decreasing ear canal pressure change.
Dr. Mona Selim

40. 3) Number of consecutive pressure sweeps:
• Test-retest reliability is enhanced if two tymp.
sweeps were completed prior to data
collection.
∀ ↑ in no. of trials  ↑ static admittance due to
viscoelastic changes of M.E due to repeated
extremes of pressure change.
Dr. Mona Selim

41. VIII) Tympanometry in infants:
Neonates
• Tympanograms recorded from infant ears are
influenced by developmental changes in the
anatomy of the ext. ear.
• Bony floor of the ext.canal is not well formed in
neonates  highly compliant ext. canal wall 
higher incidence of notched tympanograms.
• By the age of 10 days, notched tympanograms
decline to about 20%.
• Older infants: adult form nearly by the 3rd month.
Dr. Mona Selim

42. X) Advantages of tympanometry:
• Quick.
• Inexpensive.
• Non-invasive.
• Easily tolerated by most subjects.
• Requires no behavioral response.
• Reveals M.E abnormalities that may not be
detected by behavioral tests.
• No need for sound – treated room.
Dr. Mona Selim

43. XI) Limitations of tympanometry
A) Subject:
• Uncooperative (child, M.R).
• Ear atresia.
• Affected by movement.
• Old age  collapsed ear canal.
• Dual lesion.
B) Equipment:
• Calibration.
C) Physician:
• Unqualified.
Dr. Mona Selim

44. Eustachian Tube Function Tests
A) Intact T.M.
• TPP near atmospheric pressure  no ET
dysfunction suspected.
• TPP significantly -ve  ask patient to
perform Valsalva, then repeat tympanogram
 -ve pressure should resolve
(good ET function).
Dr. Mona Selim

45. Eustachian Tube Function Tests
B) Perforated T.M.
• E.T is normally closed.
• +ve or –ve press. can be built through
perforated T.M. (if not)  patulous E.T.
• After swallowing  change in pressure
occurs (good ET function).
Dr. Mona Selim

46. Eustachian Tube Function Tests
If NO change occurs after swallowing:
• Ask patient to perform valsalva or Toynbee
• Repeat tympanogram
*Change in pressure *No change in pressure
ET works under pressure Poor ET function
Dr. Mona Selim

47. Diagnosis of patulous E.T (with
).intact T.M
• Perform tympanometry.
• Hold the pressure at TPP.
• Switch system to the AR decay mode
with stimulus turned off.
• Perform 3 recordings.
Dr. Mona Selim

48. Dr. Mona Selim

49. Dr. Mona Selim