Listeners with normal hearing and cochlear implants localize speech in noise and reverberation

What is it about?

This study examined how noise and or reverberation affect the ability of listeners with normal hearing (NH) and with bilateral cochlear implants (BCIs) to localize speech. Virtual localization was measured in quiet, and different levels of noise (at +8, +4, 0, -4, and -8 dB SNR; the higher SNR the less the noise) in anechoic and reverberant environments (0.2, 0.6, and 0.9s RT60; the longer RT the more echo effect). A 3-word phrase was presented at normal conversational level (70 dB SPL) from 9 simulated locations in the frontal horizontal plane (±90°), with the noise source at 0° (in front). Results indicate BCIs users had significantly poorer localization than listeners with NH in all conditions. BCI users’ performance started to decrease at a higher SNR (+4 dB) and shorter RT60 (0.2 s) than listeners with NH (−4 dB and 0.6 s). The combination of noise and reverberation began to degrade localization of BCI users at a higher SNR and a shorter RT60 than listeners with NH. The information obtained should be useful for refining cochlear implant processing strategies and developing cochlear implant rehabilitation plans to optimize binaural benefit for BCI users in everyday listening situations.

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Why is it important?

Typical listening environments contain noise and reverberation. Despite great strides in improving speech perception performance, cochlear implant users even with two implants still have difficulty localizing sounds in noise and reverberation. However, there have been no systematic investigations of the combined effects of noise and reverberation on localization performance for listeners with bilateral cochlear implants (BCIs). This study simulate listening environments with different levels of noise and reverberation. The information obtained extends our understanding of binaural processing ability in real-life situations and should be useful for refining cochlear implant processing strategies and developing cochlear implant rehabilitation plans to optimize binaural benefit for BCI users in everyday listening situations.

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