振巾変調脈音による正常耳 Perstimulatory Adaptation の観察

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The present paper was concerned with the observations of perstimulatory auditory adaptation in the normal ear using the amplitude modulated tone. A pure tone, with a frequency of 1000cps in intensity of 50db above subjective threshold, was presented to the ear in different patterns as follows:(1) continuous presentation.(2) amplitude modulated presentations in the form of trapezoidal change, with modulation rate from 2db to 30db and modulation frequency of 4cps.(3) interrupted presentation with a repitition period of 250msec, a duty cycle of 50%, and a rise-decay time of 40msec.Perstimulatory auditory adaptation was measured by means of the binaural balancing technique with the matching time of 15sec.The following results were obtained:(1) An amount of perstimulatory auditory adaptation after 5 minutes was maximum in the contiuous tone, minimum in the interrupted, and intermediate in the amplitude modulated.Particularly, in the stimulation of the amplitude modulated tone, the degree of adaptation loss decreased with the increase of amplitude modulation rate.(2) Most of the test ears showed no adaptation loss for amplitude modulated tones with amplitude modulation rate of more than 10db.It was suggested that auditory stimulus in periodic fluctuation of intensity could bring about disappearance or decrease of perstimulatory adaptation in the normal ear as well as in the interrpted tone.
社団法人日本耳鼻咽喉科学会の論文