PERCEPTUAL ORGANIZATION OF SEQUENTIAL STIMULI IN LISTENERS WITH COCHLEAR HEARING-LOSS

The perceptual organization of sequential stimuli presumably depends i n part on the fidelity with which acoustic cues are encoded in the aud itory system. The purpose of this study was to examine the effects of cochlear hearing loss on two measures of sequential processing that re ly on spectre-temporal information. The results of a gap detection/dis crimination task indicated that listeners with cochlear hearing loss e xhibited particular difficulty discriminating gaps between tonal marke rs that were disparate in frequency. Performance improved when the dis parate tones were embedded into a sequence of alternating low- and hig h-frequency tones that may have facilitated the perceptual parsing of the stimuli into separate auditory streams. However, performance for l isteners with cochlear hearing loss was generally poorer than that of normal-healing listeners and did not appear to be related to threshold in quiet or to frequency selectivity. The results of a melody recogni tion task that required a target melody to be ''heard out'' from simul taneous competing melodies also indicated generally poorer performance on the part of the listeners with hearing loss, although the pattern of results across all listeners was highly idiosyncratic. It was concl uded that cochlear hearing loss deleteriously affects the processes un derlying perceptual organization of sequential stimuli. In particular, perceptual organization in the presence of cochlear hearing loss appe ars to require a greater frequency separation between presumed auditor y streams in comparison to normal-hearing listeners.