1978 Volume 21 Issue 6 Pages 653-659
Extratympanic electrocochleography with Sanei Sokki 7S11 without anesthesia was performed on 14 normal-hearing subjects. As the active electrode a silver ball electrode was placed on the posteriorsuperior part of the tympanic annulus. As the reference electrode and the ground electrode EEG disc electrodes were placed on the ipsilateral ear lobe and the root of nose respectively. Click was delivered from TDH 49 ear phone.
AP response threshold was 0dB to 10dB above the subjective threshold. Maximum of N1 amplitude was 2.7μV to 6.3μV. N1 amplitude-intensity function and N1 latency-intensity function were obtained. L curve and H curve were distinguished. Three kinds of AP wave (N1 only, N1N2, N1N2N3) were observed at high intensities. Wave form was deformed at 320Hz high pass filter, but was not changed at high pass filter lower than 80Hz. Clear response was recorded averaging 8 responses at high intensity and 32 responses at low intensity. Negative SP alone was recorded on all subjects. -SP visual detection threshold was 60dB to 80dB (above normal subjective threshold). -SP/AP ratio was 0.20 on the average and 0.053 on the standard deviation at 80dB.
The results of extratympanic electrocochleography using silver ball electrode was compared with that of electrocochleography using other electrodes, and clinical usefulness of this method was discussed.