Preserved acoustic hearing in cochlear implantation improves speech perception

Area of Science:

• Audiology
• Hearing Science
• Biomedical Engineering

Background:

• Cochlear implant (CI) recipients increasingly have preserved acoustic hearing, leading to bilateral acoustic hearing.
• Clinical guidelines are lacking for audiometric criteria and amplification recommendations for this population.
• The necessary acoustic bandwidth for speech perception benefit and the advantages of bilateral hearing remain unclear.

Purpose of the Study:

• To compare speech perception benefit from acoustic hearing in the CI ear versus the non-implanted ear.
• To evaluate if bilateral acoustic hearing provides greater benefit than unilateral hearing.

Main Methods:

• A within-participant study compared speech recognition in four conditions: CI alone, CI + non-implanted ear acoustic hearing, CI + implanted ear acoustic hearing, and CI + bilateral acoustic hearing.
• Low-pass filters assessed acoustic bandwidth effects with amplification.
• Benefit was measured in quiet and diffuse/single-source background noise.

Main Results:

• Equivalent acoustic bandwidth provided similar speech perception benefit in either ear.
• The non-implanted ear showed greater benefit in wideband conditions due to better thresholds.
• Bilateral acoustic hearing significantly improved speech perception over unilateral hearing, but only in diffuse background noise.

Conclusions:

• Amplification is supported for the CI ear when residual hearing is present.
• The benefits of bilateral acoustic hearing (hearing preservation) are best evaluated in diffuse background noise, not in quiet or with coincident sound sources.