Audio-visual speech intelligibility benefits with bilateral cochlear implants when talker location varies

Area of Science:

• Audiology and Speech-Language Pathology
• Neuroscience
• Biomedical Engineering

Background:

• Bilateral cochlear implants (CIs) enhance sound localization compared to single implants.
• Improved localization may help users focus on speech and access visual cues in noisy environments.
• The real-world benefits of bilateral CIs in dynamic audio-visual settings remain largely untested.

Purpose of the Study:

• To objectively measure the speech intelligibility benefits of bilateral CIs in audio-only and audio-visual conditions.
• To compare bilateral CI performance against single-ear performance in challenging listening scenarios.
• To investigate the role of spatial localization in audio-visual speech perception for bilateral CI users.

Main Methods:

• Seven bilateral CI users participated in a novel dynamic spatial audio-visual test.
• Participants completed speech reception threshold (SRT) tests in spatially distributed noise.
• Tests included audio-only and audio-visual conditions with and without visual distractors.

Main Results:

• Bilateral listening showed an average SRT improvement of 9 dB (audio-visual) and 3 dB (audio-only) over the better single ear.
• Visual cues improved bilateral performance by an average of 5 dB.
• Unilateral device use did not yield similar benefits, likely due to impaired localization.

Conclusions:

• Bilateral CIs offer significant speech intelligibility advantages over single CIs, particularly in dynamic audio-visual settings.
• The ability to localize sound sources is crucial for maximizing the benefits of bilateral CIs with visual information.
• These findings suggest greater everyday benefits and improved cost-effectiveness for bilateral CI use than previously estimated.