Abstract
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
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