Monaural Beamforming in Bimodal Cochlear Implant Users: Effect of (A)symmetric Directivity and Noise Type

• Published in: PloS one Vol. 11; no. 8; p. e0160829
• Main Authors: Devocht, Elke M J, Janssen, A Miranda L, Chalupper, Josef, Stokroos, Robert J, George, Erwin L J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18.08.2016; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Analysis; Audiology; Auditory Threshold; Beamforming; Biology and Life Sciences; Cochlea; Cochlear Implantation; Cochlear Implants; Complications and side effects; Configuration management; Directivity; Ears & hearing; Engineering and Technology; Female; Hearing aids; Hearing disorders; Humans; Intelligibility; Listening; Male; Medicine and Health Sciences; Mental health; Microphones; Microprocessors; Middle Aged; Neurosciences; Noise; Noise levels; Patient outcomes; Performance evaluation; Physical Sciences; Prostheses and implants; Prosthesis Design; Risk factors; Social Sciences; Speech; Speech Intelligibility; Speech Perception; Variation; Young Adult; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0160829

To evaluate monaural beamforming in bimodally aided cochlear implant (CI) users. The study enrolled twelve adult bimodal listeners with at least six months of CI-experience and using a contralateral hearing aid (HA) most of the daytime. Participants were uniformly fitted with the same CI speech processor and HA, giving access to an identical monaural beamformer in both ears. A within-subject repeated measures design evaluated three directional configurations [omnidirectional, asymmetric directivity (in CI alone) and symmetric directivity (in both CI and HA)] in two noise types [stationary and fluctuating]. Bimodal speech reception thresholds (SRT) as well as listening effort ratings were assessed in a diffuse noise field. Symmetric monaural beamforming provided a significant SRT improvement of 2.6 dB SNR, compared to 1.6 dB SNR for asymmetric monaural beamforming. Directional benefits were similarly observed in stationary and fluctuating noise. Directivity did not contribute to less listening effort in addition to improvement in speech intelligibility. Bimodal performance was about 7 dB SNR worse in fluctuating than in stationary noise. Monaural beamforming provided substantial benefit for speech intelligibility in noise for bimodal listeners. The greatest benefit occurred when monaural beamforming was activated symmetrically in both CI and HA. Monaural beamforming does not bridge the gap between bimodal and normal hearing performance, especially in fluctuating noise. Results advocate further bimodal co-operation. This trial was registered in www.trialregister.nl under number NTR4901.