Comparison of two channel selection criteria for noise suppression in cochlear implants

The performance of current channel selection criteria used in cochlear implant (CI) devices (e.g., maximum selection criterion used in ACE) degrades significantly in the presence of noise. In noisy backgrounds, coding strategies that select the "right" channels for stimulation could potentially produce substantial improvements in intelligibility. In this study, the performance of two alternative channel selection criteria is assessed in terms of intelligibility and subjective quality with CI users in noise. The performance is compared against that of the maximum selection scheme employed in the ACE strategy (comparison is also made with the CIS strategy). Sentences were presented to seven CI users in speech weighted noise (-5, 0, and 5 dB SNR). Both channel selection criteria were implemented under ideal conditions where a priori knowledge of the target and masker was assumed. This was done to assess the full potential benefit of selecting the "right" channels for stimulation in noisy backgrounds. Substantial intelligibility improvement relative to the CI users' daily strategy (i.e., ACE or CIS) was achieved with the two different channel selection criteria under all noisy conditions considered. No significant difference in subjective quality of noisy speech processed by the two channel selection criteria was observed.