Binaural fusion in single-sided deaf cochlear implant users

Area of Science:

• Audiology
• Neuroscience
• Biomedical Engineering

Background:

• Single-sided deafness (SSD) cochlear implant (CI) users often experience challenges with spatial hearing.
• This difficulty may stem from impaired fusion between acoustic and electric hearing signals.

Purpose of the Study:

• To investigate the extent of binaural fusion in adult SSD CI patients.
• To understand how acoustic and electric hearing interact for spatial perception.

Main Methods:

• Eight adult SSD CI patients were assessed for binaural fusion.
• Participants evaluated auditory images (one vs. two), sound diffuseness, and sound lateralization in a virtual environment using speech and non-speech stimuli.

Main Results:

• Binaural fusion was highly variable among participants, with a single auditory image perceived only 40.23% of the time.
• Sound diffuseness differed significantly based on stimulus type (words/environmental sounds vs. sentences/tones).
• Perceived auditory images were generally lateralized centrally when one image was heard, and broadly distributed when two were perceived.

Conclusions:

• Binaural fusion capabilities in SSD CI users are significantly lower compared to bilateral CI users.
• Potential contributing factors include differences in acoustic-electric stimulation patterns and interaural frequency mismatches.