Spatial Speech-in-Noise Performance in Bimodal and Single-Sided Deaf Cochlear Implant Users

Area of Science:

• Audiology
• Neuroscience
• Biomedical Engineering

Background:

• Cochlear implants (CI) aim to restore hearing, but spatial speech perception in noise remains challenging.
• Understanding how different CI user groups process spatial audio is crucial for improving device efficacy.

Purpose of the Study:

• To compare spatial speech-in-noise performance between bimodal CI listeners and CI single-sided deaf listeners.
• To investigate the presence of binaural summation and "listening with the better ear" strategies in these CI groups.

Main Methods:

• Speech reception thresholds were measured in a controlled laboratory setting simulating spatial acoustic scenes.
• Spatial release from masking (SRM) was calculated for monaural and binaural listening conditions.
• Performance was compared between bimodal CI users, CI single-sided deaf users, and a normal-hearing control group.

Main Results:

• Bimodal CI listeners exhibited significantly lower SRM compared to CI single-sided deaf listeners.
• Neither CI group demonstrated a binaural summation effect; performance did not improve with two devices over the best single device.
• Both CI groups employed a "listening with the better ear" strategy, selectively utilizing the better-performing ear/device based on spatial context.

Conclusions:

• Spatial speech-in-noise processing differs between bimodal CI users and CI single-sided deaf individuals.
• CI users do not exhibit binaural summation but rather adopt a "better ear" listening strategy.
• The effectiveness of the "better ear" strategy depends on the spatial scenario and individual hearing loss characteristics.