Channel weights for speech recognition in cochlear implant users

The purpose of this study was to develop and validate a method of estimatin g the relative "weight'' that a multichannel cochlear implant user places o n individual channels, indicating its contribution to overall speech recogn ition. The correlational method as applied to speech recognition was used b oth with normal-hearing listeners and with cochlear implant users fitted wi th six-channel speech processors. Speech was divided into frequency bands c orresponding to the bands of the processor and a randomly chosen level of c orresponding filtered noise was added to each channel on each trial. Channe ls in which the signal-to-noise ratio was more highly correlated with perfo rmance have higher weights, and conversely, channels in which the correlati ons were smaller have lower weights. Normal-hearing listeners showed approx imately equal weights across frequency bands. In contrast, cochlear implant users showed unequal weighting across bands, and varied from individual to individual with some channels apparently not contributing significantly to speech recognition. To validate these channel weights, individual channels were removed and speech recognition in quiet was tested. A strong correlat ion was found between the relative weight of the channel removed and the de crease in speech recognition, thus providing support for use of the correla tional method for cochlear implant users. (C) 2001 Acoustical Society of Am erica. [DOI: 10.1121/1.1322021].