Preprocessing Strategies and Speech Perception Through Cochlear Implants: A Systematic Review

Abstract

Speech perception in the presence of competing noise is a challenging task for most individuals with cochlear implants (CI). Several advanced technologies are available in different cochlear implant systems to provide comfort in listening and enhanced speech perception in noisy environments without degrading the performance in quiet settings. The implementation of pre-processing strategy is an effective method for enhancing the signal quality in challenging signal-to-noise conditions. This study systematically reviews the articles published in the past nineteen years (2002-2021) regarding the various pre-processing strategies available in the major cochlear implant devices (Cochlear Ltd, Advanced Bionics, Med-EL, Digisonic). This review gives a broad overview of the device descriptions related to noise reduction strategies and the performance across listening environments. The studies concerning speech perception performance across adults and children were reviewed. Several pre-processing strategies are available in the cochlear implant devices, including Adaptive Dynamic Range Optimization (ADRO), Automatic Sensitivity Control (ASC), VoiceTrack, ClearVoice, BEAM, ZOOM, and SCAN. This review analyzed the speech perception benefits of each of these strategies and their performance in quiet and noise conditions. The evidence from the literature indicates that the enhanced performance with pre-processing strategies highlights the importance of incorporating appropriate noise reduction algorithms in CI devices.