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. 2014 Sep-Oct;35(5):580-4.
doi: 10.1097/AUD.0000000000000044.

Binaural enhancement for bilateral cochlear implant users

Christopher A Brown  1
Affiliations

Binaural enhancement for bilateral cochlear implant users

Christopher A Brown. Ear Hear. 2014 Sep-Oct.

Abstract

Objectives: Bilateral cochlear implant (BCI) users receive limited binaural cues and, thus, show little improvement to speech intelligibility from spatial cues. The feasibility of a method for enhancing the binaural cues available to BCI users is investigated. This involved extending interaural differences of levels, which typically are restricted to high frequencies, into the low-frequency region.

Design: Speech intelligibility was measured in BCI users listening over headphones and with direct stimulation, with a target talker presented to one side of the head in the presence of a masker talker on the other side. Spatial separation was achieved by applying either naturally occurring binaural cues or enhanced cues.

Results: In this listening configuration, BCI patients showed greater speech intelligibility with the enhanced binaural cues than with naturally occurring binaural cues.

Conclusions: In some situations, it is possible for BCI users to achieve greater speech intelligibility when binaural cues are enhanced by applying interaural differences of levels in the low-frequency region.

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Figures

Fig. 1
Fig. 1
Interaural differences of levels as a function of frequency for a broadband noise presented 90 degrees to one side, and recorded with a KEMAR.
Fig. 2
Fig. 2
Speech intelligibility for five BCI listeners in three conditions. In the “diotic” condition, no binaural cues were applied to either the target or the masker. In the “natural” condition, binaural cues were applied, which included the ILD-by-frequency function shown in Figure 1, and a whole-waveform ITD of 600 μs. In the “enhanced” condition, the stimulus mixture created in the natural condition was subjected to the ITD-to-ILD algorithm, which applied low-frequency ILD cues based on the instantaneous ITD information. The difference in performance between the diotic and natural conditions represents the SRM that the participants would receive typically. The difference between the natural and enhanced conditions represents the additional SRM provided by the binaural enhancement. BCI indicates bilateral cochlear implant; ILD, interaural differences of levels; ITD, interaural differences of time; SRM, spatial release from masking.
See this image and copyright information in PMC

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