An attempt to measure the hearing thresholds for high‐frequency sounds by using the auditory brain‐stem response

Abstract

Recently, devices using high‐power ultrasounds are increasing. However, influences of high level ultrasounds on human are not fully understood. Psychophysical studies show that the hearing thresholds exceed 80 dB SPL at a frequency above 20 kHz. It is reported that high frequency sounds above 20 kHz affect activities in the human nervous system. In order to examine whether the peripheral auditory system can be activated by high‐frequency sounds, an attempt is made to measure the auditory brainstem response (ABR) for the frequency range between 4 and 20 kHz. In preliminary experiments, the ABR was measured for a tone pip with the center frequency of 14 kHz. However, the ABR was not clearly observed above 16 kHz. The thresholds determined by the ABR were approximately 40 dB larger than the psychophysical thresholds. The ABR was evoked by low‐frequency components of the tone pip at the high presentation levels.