Properties of acoustic reflex adaptation to pure tones and one-third octave bands of noise.

Acoustic reflex thresholds were obtained by a computerized threshold search procedure for two pure tones (500 and 2000 Hz) and two one-third octave bands of noise (436--553 and 1752--2253 Hz). The stimuli were presented at 5- and 10-dB sensation level (re: reflex threshold) with an interstimulus interval of at least 80 sec. Acoustic reflex adaptation was measured at predetermined stimulus durations of 15, 30, 45, and 60 sec. For the pure tone stimuli, reflex adaptation was found to be frequency dependent, with the 2000-Hz tone producing significantly greater adaptation than the 500-Hz pure tone. The main effects of sensation level and duration were not statistically significant for the pure tone stimuli. Results for the noise stimuli revealed no significant differences in reflex adaptation for the effects of frequency, sensation level, and duration. The overall intersubject variability of acoustic reflex adaptation was greater for the noise stimuli.