Investigating the effect of cochleotopic region on temporal processing using binaural fusion

Abstract

Processing of temporal information in a signal may vary across apical, mid and basal regions of the cochlea—there is evidence for this in both cochlear-implant and typical-hearing listeners. This effect may also be task dependent and has not been studied with respect to binaural fusion. Fusion depends on tracking the temporal fluctuations across ears which can be manipulated by varying the interaural correlation (IC) of a signal. To investigate the effect of place of stimulation on fusion, 9 bilateral cochlear implant users were presented with 1000 Hz pulse trains with varying envelope IC. An apical, mid, and basal electrode were separately selected as reference, each of which was then paired with five electrodes in the contralateral ear, spread across the array. Listeners indicated the spatial diffuseness and the number of auditory “images” of the perceived sound by manipulating a visual representation of their perception superimposed on a picture of a head. Preliminary results indicate that, for optimally paired electrodes, fusion increases similarly for the three regions of the cochlea with increasing IC, and when IC is 1, the degree of fusion is comparable across regions. Processing of temporal information for binaural fusion is not significantly different across cochleotopic regions.