Behavioral measures of cochlear gain reduction and gain reduction in with normal hearing or minimal cochlear hearing loss

This is a continuation of a study examining the relationship between cochlear hearing loss and various psychoacoustic measures thought to be related to cochlear function. In the listeners tested, thresholds for long tones ranged from well within the clinically normal range to just outside this range. Where thresholds were elevated, other clinical tests were consistent with a cochlear origin. Because the medial olivocochlear reflex (MOCR) decreases the gain of the cochlear active process in response to sound, when possible, measures were made with short stimuli. Signal frequencies were 2, 4, and 8 kHz. Maximum gain was estimated by measuring the threshold masker level for a masker at the signal frequency and a masker well below the signal frequency. The effect of signal duration on threshold was measured using 10 and 200-signals. One point on the lower leg of the input/output function was measured by finding the threshold masker level for a masker slightly less than one octave below the signal frequency ne...