A 30-year-old woman presents with progressive bilateral conductive hearing loss. Audiometry shows bilateral conductive hearing loss with a characteristic notch in bone conduction at 2000 Hz. Tympanometry shows a type As pattern. This notch is called:

• A A 4000 Hz notch consistent with noise-induced hearing loss
• B A high-frequency sloping loss consistent with presbycusis
• C Paracusis Willisii — improved hearing in noise
• D Carhart's notch — a mechanical artefact of stapedial fixation, not true cochlear loss ✓

Explanation

Carhart's notch is a characteristic 2000 Hz dip in the bone-conduction audiogram of patients with otosclerosis. It is a mechanical artefact resulting from the loss of the inertial component of bone conduction due to stapedial fixation — it does not represent true cochlear sensorineural damage. Carhart's notch disappears after successful stapedectomy, confirming its mechanical rather than cochlear origin. The 4000 Hz notch is characteristic of noise-induced hearing loss.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.