Effects of electrode separation between speech and noise signals on consonant identification in cochlear implants
Journal of the Acoustical Society of America
The aim of the present study was to examine cochlear implant ͑CI͒ users' perceptual segregation of speech from background noise with differing degrees of electrode separation between speech and noise. Eleven users of the nucleus CI system were tested on consonant identification using an experimental processing scheme called "multi-stream processing" in which speech and noise stimuli were processed separately and interleaved. Speech was presented to either ten ͑every other electrode͒ or six
... rodes ͑every fourth electrode͒. Noise was routed to either the same ͑the "overlapped" condition͒ or a different set of electrodes ͑the "interlaced" condition͒, where speech and noise electrodes were separated by one-and two-electrode spacings for ten-and six-electrode presentations, respectively. Results indicated a small but significant improvement in consonant recognition ͑5%-10%͒ in the interlaced condition with a two-electrode spacing ͑approximately 1.1 mm͒ in two subjects. It appears that the results were influenced by peripheral channel interactions, partially accounting for individual variability. Although the overall effect was small and observed from a small number of subjects, the present study demonstrated that CI users' performance on segregating the target from the background might be improved if these sounds were presented with sufficient peripheral separation.