On impedance audiometry, a patient with Eustachian tube dysfunction shows a tympanogram with the compliance peak shifted to a highly negative pressure (e.g., -300 daPa). This is classified as which type?
- A Type C ✓
- B Type As
- C Type A
- D Type Ad
Correct answer: A. Type C
Explanation
Type A tympanogram shows the compliance peak at negative pressure (typically more negative than -100 daPa), indicating negative middle ear pressure from Eustachian tube dysfunction with patent middle ear space. Type C has peak at 0 daPa; Type As is shallow (reduced compliance, e.g., otosclerosis); Type Ad is hypermobile (ossicular discontinuity or flaccid eardrum).
Reference: Katz Handbook of Clinical Audiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.