Benefits of Adaptive Signal Processing in a Commercially Available Cochlear Implant Sound Processor.

OBJECTIVE: Cochlear implant recipients often experience difficulty understanding speech in noise. The primary objective of this study was to evaluate the potential improvement in speech recognition in noise provided by an adaptive, commercially available sound processor that performs acoustic scene classification and automatically adjusts input signal processing to maximize performance in noise. RESEARCH DESIGN: Within-subjects, repeated-measures design. SETTING: This multicenter study was conducted across five sites in the U.S.A. and Australia. PATIENTS: Ninety-three adults and children with Nucleus Freedom, CI422, and CI512 cochlear implants. INTERVENTION: Subjects (previous users of the Nucleus 5 sound processor) were fitted with the Nucleus 6 sound processor. Performance was assessed while these subjects used each sound processor in the manufacturer's recommended default program (standard directionality, ASC + ADRO for the Nucleus 5 processor and ASC + ADRO and SNR-NR with SCAN for the Nucleus 6 sound processor). The subjects were also evaluated with the Nucleus 6 with standard directionality, ASC + ADRO and SNR-NR enabled but SCAN disabled. MAIN OUTCOME MEASURES: Speech recognition in noise was assessed with AzBio sentences. RESULTS: Sentence recognition in noise was significantly better with the Nucleus 6 sound processor when used with the default input processing (ASC + ADRO, SNR-NR, and SCAN) compared to performance with the Nucleus 5 sound processor and default input processing (standard directionality, ASC + ADRO). Specifically, use of the Nucleus 6 at default settings resulted in a mean improvement in sentence recognition in noise of 27 percentage points relative to performance with the Nucleus 5 sound processor. Use of the Nucleus 6 sound processor using standard directionality, ASC + ADRO and SNR-NR (SCAN disabled) resulted in a mean improvement of 9 percentage points in sentence recognition in noise compared to performance with the Nucleus 5. CONCLUSION: The results of this study suggest that the Nucleus 6 sound processor with acoustic scene classification, automatic, adaptive directionality, and speech enhancement in noise processing provides significantly better speech recognition in noise when compared to performance with the Nucleus 5 processor.

Evaluation of speech recognition of cochlear implant recipients using a personal digital adaptive radio frequency system.

BACKGROUND: Previous research supports the use of frequency modulation (FM) systems for improving speech recognition in noise of individuals with cochlear implants (CIs). However, at this time, there is no published research on the potential speech recognition benefit of new digital adaptive wireless radio transmission systems. PURPOSE: The goal of this study was to compare speech recognition in quiet and in noise of CI recipients while using traditional, fixed-gain analog FM systems, adaptive analog FM systems, and adaptive digital wireless radio frequency transmission systems. RESEARCH DESIGN: A three-way repeated-measures design was used to examine performance differences among devices, among speech recognition conditions in quiet and in increasing levels of background noise, and between users of Advanced Bionics and Cochlear CIs. STUDY SAMPLE: Seventeen users of Advanced Bionics Harmony CI sound processors and 20 users of Cochlear Nucleus 5 sound processors were included in the study. DATA COLLECTION AND ANALYSIS: Participants were tested in a total of 32 speech-recognition-in noise-test conditions, which included one no-FM and three device conditions (fixed-gain FM, adaptive FM, and adaptive digital) at the following signal levels: 64 dBA speech (at the location of the participant) in quiet and 64 dBA speech with competing noise at 50, 55, 60, 65, 70, 75, and 80 dBA noise levels. RESULTS: No significant differences were detected between the users of Advanced Bionics and Cochlear CIs. All of the radio frequency system conditions (i.e., fixed-gain FM, adaptive FM, and adaptive digital) outperformed the no-FM conditions in test situations with competing noise. Specifically, in conditions with 70, 75, and 80 dBA of competing noise, the adaptive digital system provided better performance than the fixed-gain and adaptive FM systems. The adaptive FM system did provide better performance than the fixed-gain FM system at 70 and 75 dBA of competing noise. At the lower noise levels of 50, 55, 60, and 65 dBA, no significant differences were detected across the three systems, and no significant differences were found across the quiet conditions. In all conditions, performance became poorer as the competing noise level increased. CONCLUSIONS: In high levels of noise, the adaptive digital system provides superior performance when compared to adaptive analog FM and fixed-gain FM systems.