Temporal summation of the acoustic reflex in normal and sensorineural hearing-impaired ears.

Psychophysical and acoustic reflex temporal summation measures were obtained on normal-hearing and sensorineural hearing-impaired persons. Bursts of one-third octave noise with center frequencies of 500, 1000, 2000, and 4000 Hz and durations of 15, 20, 50, 100, 200, and 300 msec were used as stimuli. Reflexes were obtained using an acoustic impedance measuring technique. Results demonstrated that the duration of the noise stimuli had a profound effect on the acoustic reflex response and that the ear with Ménière's disease was clearly distinguishable from the normal ear by both psychophysical and acoustic reflex temporal summation measurements. The presbycusic subjects were separated from the normal subjects to a greater extent in the psychophysical data at the higher frequencies. The reflex thresholds for the noise bands and durations used in this study occurred at lower sound pressure levels than those previously obtained. The normal-hearing subjects failed to show any differences in either psychophysical or acoustic reflex temporal summation as a function of stimulus frequency.