A STUDY OF RECRUITMENT PHENOMENON OF AUDITION AND ITS MECHANISM

This study was undertaken in order to know what are indispensable for understanding theoretically the mechanism of recruitment phenomenon.The following results were obtained:(1) In human subjects.By determinating auditory loudness levels, the auther examined whether 20 ears with acoustic trauma have recruitment phenomenon or not, and obtained the fact that recruitment phenomenon was clearly noticed in the all ears.(2) In animals(guinea pigs).The auther has observed the changes of the intensity function of cochlear microphonics(CM) and whole nerve action potential(N1) of acoustic nerves of the animals, which had been exposed to intense sound.The remarkable recruiting slopes were observed in the N1, and they were similar to the recruiting slopes noticed in pathological human audition.On the other hand, in the function curves of CM the recruiting slopes were found only at non-linear portion of the curves.With these results, the auther has discussed a hypothesis on the mechanism of recruitment phenomenon.