Auditory Steady State Responses to Sinusoidally Amplitude-Modulated Tones

Abstract

Auditory steady state responses elicited with sinusoidally amplitude-modulated tones of 0.5 to 4kHz were recorded in 9 adult subjects with normal hearing. The magnitude of the responses was greatest at 40-Hz modulation rate and at 90% modulation depth. The magnitude tended to decrease as a function of stimulus frequency. The lapse of time was measured from the minus peak of the amplitude-modulated tones to the following positive peak of the responses at the active electrode placed on the forehead just beneath the hairline. Its approximate values ranged between 12 and 15ms. The mean latency of the responses measured following Diamond Method was 12.2ms. A significant effect of sleep was found in the responses. The magnitude of the responses in deep sleep state frequently decreased less than 1/3 of that in awake state.