Compensating for impaired prosody perception in cochlear implant recipients: A novel approach using speech preprocessing
Due to inherent device limitations, cochlear implant (CI) recipients are provided with greatly reduced pitch information. However, detecting changes in pitch is necessary to perceive intonation, a main feature of prosody. Therefore, CI recipients’ ability to perceive prosody is typically below that of normal-hearing subjects. We propose a novel preprocessing algorithm to enhance intonation perception by broadening the range of pitch changes in speech signals. To proof this concept, we have developed the pitch range extension (PREX) algorithm. PREX is capable of low-delay pitch modifications to speech signals. In addition, it provides automatic and intonation based amplification of pitch movements. In an evaluation with 23 CI recipients, the proposed algorithm significantly improved intonation perception in a question vs. statement experiment. However, the improved performance of CI subjects was still inferior to the performance of normal-hearing subjects. The results support the idea that preprocessing algorithms can improve the perception of prosodic speech features. Furthermore, we suggest utilizing the PREX algorithm for individualized treatment and rehabilitation.
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