Simulating the dual-peak excitation pattern produced by bipolar stimulation of a cochlear implant: Effects on speech intelligibility.

Simulating the dual-peak excitation pattern produced by bipolar stimulation of a cochlear implant: Effects on speech intelligibility.
Hear Res. 2014 Nov 15;319C:32-47
Authors: Mesnildrey Q, Macherey O
Abstract
Several electrophysiological and psychophysical studies have shown that the spatial excitation pattern produced by bipolar stimulation of a cochlear implant (CI) can have a dual-peak shape. The perceptual effects of this dual-peak shape were investigated using noise-vocoded CI simulations in which synthesis filters were designed to simulate the spread of neural activity produced by various electrode configurations, as predicted by a simple cochlear model. Experiments 1 and 2 tested speech recognition in the presence of a concurrent speech masker for various sets of single-peak and dual-peak synthesis filters and different numbers of channels. Similarly as results obtained in real CIs, both monopolar (MP, single-peak) and bipolar (BP + 1, dual-peak) simulations showed a plateau of performance above 8 channels. The benefit of increasing the number of channels was also lower for BP + 1 than for MP. This shows that channel interactions in BP + 1 become especially deleterious for speech intelligibility when a simulated electrode acts both as an active and as a return electrode for different channels because envelope information from two different analysis bands are being conveyed to the same spectral location. Experiment 3 sho...

Source: Hearing Research - November 15, 2014 Category: Audiology Authors: Mesnildrey Q, Macherey O Tags: Hear Res Source Type: research