A channel-selection criterion for suppressing reverberation in cochlear implants

• DOI: 10.1121/1.3559683
• Publication Date: 2011-05-10T23:14:01Z
• Authors: Kostas Kokkinakis; Oldooz Hazrati; Philipos C. Loizou
• Keywords: Intelligibility (philosophy)

Little is known about the extent to which reverberation affects speech intelligibility by cochlear implant (CI) listeners. Experiment 1 assessed CI users' performance using Institute of Electrical and Electronics Engineers (IEEE) sentences corrupted with varying degrees reverberation. Reverberation times 0.30, 0.60, 0.80, 1.0 s were used. Results indicated that for all subjects tested, decreased exponentially an increase in time. A decaying-exponential model provided excellent fit data. 2 evaluated (offline) a coding strategy suppression channel-selection criterion based on signal-to-reverberant ratio (SRR) individual frequency channels. The SRR reflects implicitly energies signal originating from early (and direct) reflections late reflections. Channels larger than preset threshold selected, while channels smaller zeroed out. highly reverberant scenario proposed led substantial gains (over 60 percentage points) over subjects' daily strategy. Further analysis reduces temporal envelope smearing effects introduced also diminishes self-masking responsible flattened formants.