Carhart notch

Car·hart notch

(kahr'hahrt noch)
Isolated depression around 2000 Hz in the bone-conduction audiogram of patients with otosclerosis.
See: air-bone gap
See also: otosclerosis
References in periodicals archive ?
An audiogram demonstrated a right maximal conductive loss and a Carhart notch. Computed tomography (CT) demonstrated a 2-mm lucency on the oval window (figure 1).
The Carhart notch was present on both sides, and the mean bone conduction threshold was 5 dB on 0.5-1-2-3 kHz.
All patients fulfilling the inclusion criteria of being indigenous black South Africans with progressive painless conductive hearing loss without infection or trauma, normal tympanic membrane and the presence of a Carhart notch on the audiogram, were included.
Clinical otosclerosis on history and presence of a Carhart notch had a 100% surgical correlation of oval window ankylosis (stapes footplate fixation) in 28 (90.3%) patients.
Pure-tone audiometry in otosclerosis: Insufficient evidence for the diagnostic value of the Carhart notch. Otolaryngol Head Neck Surg 2013;149(4):528-32.
Five ears (26.3%) had a Carhart notch on audiometry.
Interestingly, of those patients with normal CT findings, a Carhart notch was noted on audiometry in 2 of 4 ears (50%).
We also calculated the Carhart notch for each patient; this value represents the increase in the bone-conduction threshold with the largest depression at 2,000 Hz in the audiometric curve.
If a patient with a normal bone conduction threshold, allowing for the Carhart notch, undergoes surgery, it is likely that any subsequent loss of auditory acuity is due to presbycusis or some other factor.