Reliability of the cochlear microphonics in clinical electrocochleography.

Study was made on the reliability of cochlear microphonics (CM) recorded in clinical electrocochleography (ECochG) by the transtympanic electrode technique.In normal hearing subjects, the "CM-shift" was greater as the frequency was lowered at the same sound pressure, and as the sound pressure was lowered at the same frequency.The CM-shift for the frequencies from 8 kHz to 0.5 kHz was greater as the sound pressure was lowered .Such a CM-shift was observed also in other types of sensorineural deafness.As to estimation of the prognosis of sudden deafness the multiple regression analysis was made.In the various variates such as the detection threshold of CM, the out-put potential of CM at 90dB, the detection threshold of AP. the out-put potential of AP at 90dB, the -SP potential and -SP/AP ratio, there was significant regression with the detection threshold of CM in the early stage of the onset.The above results suggested that clinical ECochG CM responses may well reflect the potential of the cochlea.