The correlation between AP response and form of audiogram was examined by promontory recording in electrocochleography. In normal hearing subjects, each frequency tone of 0.5, 1, 2, 4 and 8 kHz was used as sound stimulus.
In normal hearing subjects, subjective hearing threshold above 2kHz corresponded with AP threshold.
Among each sound stimulus, 4kHz tone showed the lowest response threshold, and the shortest AP latency was obtaindd by sound stimuli 4 and 8kHz tones.
In 48 patients with hearing impairment, AP response was recorded by 4kHz tone.
In patients with difference of pure tone threshold less than 35dB between 4 and 1kHz, AP response threshold corresponded within 15dB to pure tone threshold at 4kHz.
With shortening of difference between 4 and 1kHz pure tone threshold, AP threshold corresponded with pure tone threshold at 4kHz.
In patients with difference more than 20dB, the prolonged AP latency was detected, in other words, the prolonged AP latency was detected in proportion to the difference between 4 and 1kHz pure tone threshold.
Namely, a flat and gradual sloping form in audiogram, AP threshold corresponded roughly with the pure tone threshold at 4kHz, but an abrupt form showed the lower AP threshold than that of pure tone threshold at 4kHz and also, AP latency showed a tendency to prolongation.
抄録全体を表示