Bimodal benefit depends on the performance difference between a cochlear implant and a hearing aid

Area of Science:

• Audiology
• Neuroscience
• Biomedical Engineering

Background:

• Bimodal hearing, using a hearing aid (HA) in one ear and a cochlear implant (CI) in the other, is common for individuals with asymmetrical hearing loss.
• Understanding factors influencing bimodal benefit is crucial for optimizing auditory rehabilitation strategies.
• Previous research has explored individual device performance, but the interplay between HA and CI performance in bimodal configurations requires further investigation.

Purpose of the Study:

• To investigate the relationship between bimodal benefit and the individual performances of hearing aids (HA) and cochlear implants (CI).
• To determine if the difference in performance between HA and CI contributes to bimodal benefit.
• To identify predictors of bimodal benefit in adult listeners using combined HA and CI devices.

Main Methods:

• Fourteen adult bimodal listeners were recruited for the study.
• Speech recognition (consonant, vowel, sentence) was assessed in quiet and noise (SNRs of +5 and +10 dB) under three conditions: HA alone, CI alone, and bimodal (HA + CI).
• Correlation and regression analyses were employed to examine the relationships between bimodal benefit and device performances.

Main Results:

• Bimodal benefit was significantly associated with the performance difference between CI and HA across all tested materials.
• A smaller performance difference between the HA and CI was linked to greater bimodal benefit.
• Individual HA-only or CI-alone performance did not significantly predict bimodal benefit when the performance difference was accounted for.

Conclusions:

• Bimodal benefit is primarily determined by the effective integration of auditory information from both devices, rather than the standalone performance of either the HA or CI.
• Optimal integration, and thus greater bimodal benefit, occurs when the HA and CI exhibit similar performance levels.
• These findings suggest that audiologists should consider the similarity in device performance when counseling patients on bimodal hearing strategies.