Archives of Acoustics, 40, 1, pp. 81–92, 2015

An Influence of Directional Microphones on the Speech Intelligibility and Spatial Perception by Cochlear Implant Users

Poznan University of Medical Science, Department of Biophysics, Fredry St.10, 61-701 Poznan, Poland

Richard S. TYLER
University of Iowa Hospital & Clinics, Department of Otolaryngology—Head and Neck Surgery 21151 Pomerantz Family Pavilion 200 Hawkins Drive Iowa City, IA 52242-1089
United States

Warsaw University of Technology, Faculty of Electronics and Information Technology, Nowowiejska 15/19, 00-665 Warsaw, Poland

Department of Biostatistics, 200 Hawkins Drive, C22 GH, The University of Iowa, Iowa City, Iowa, 52242 1009, USA
United States

The objective of the study is to assess the hearing performance of cochlear implant users in three device microphone configurations: omni-directional, directional, and beamformer (BEAMformer two-adaptive noise reduction system), in localization and speech perception tasks in dynamically changing listening environments. Seven cochlear implant users aided with Cochlear CM-24 devices with Freedom speech processor participated in the study. For the localization test in quiet and in background noise, subjects demonstrated significant differences between different microphone settings. Confusion matrices showed that in about 70% cases cochlear implant subjects correctly localized sounds within a horizontal angle of 30–40◦ (±1◦ loudspeaker apart from signal source). However localization in noise was less accurate as shown by a large number of considerable errors in localization in the confusion matrices. Average results indicated no significant difference between three microphone configurations. For speech presented from the front 3 dB SNR improvements in speech intelligibility in three subjects can be observed for beamforming system compared to directional and omni-directional microphone settings. The benefits of using different microphone settings in cochlear implant devices in dynamically changing listening conditions depend on the particular sound environment.
Keywords: Localization, Bilateral cochlear implants, Adults, Microphone, Beamformer
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Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN).


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DOI: 10.1515/aoa-2015-0010