Frequency Following Response and Speech Recognition Benefit for Combining a Cochlear Implant and Contralateral...

Area of Science:

• Audiology
• Neuroscience
• Speech-Language Pathology

Background:

• Bimodal hearing (cochlear implant + hearing aid) significantly improves speech recognition for many users.
• Individual variability in bimodal benefit is high, with limited clinical tools for prediction.
• Current correlations with bimodal benefit are often based on extreme values, hindering clinical application.

Purpose of the Study:

• To investigate the relationship between neural encoding of fundamental frequency (F0) and temporal fine structure via FFR in the non-implanted ear and bimodal speech recognition benefit.
• To assess if spectral and temporal resolution in the non-implanted ear correlate with bimodal benefit.
• To explore the potential of FFR as an objective predictor of bimodal benefit.

Main Methods:

• 14 unilateral cochlear implant (CI) users with hearing aids (HA) in the non-implanted ear participated.
• Speech recognition was tested in quiet and noise for HA-alone, CI-alone, and bimodal (CI+HA) conditions.
• Frequency following response (FFR) was recorded in the non-implanted ear using a /da/ stimulus; spectral and temporal resolution were also measured.

Main Results:

• A significant correlation (r=0.83) was found between FFR F0 amplitude in the non-implanted ear and bimodal speech recognition benefit, even after controlling for pure-tone average.
• Measures of spectral and temporal resolution in the non-implanted ear did not significantly correlate with bimodal benefit.
• FFR amplitude in the non-implanted ear emerged as a strong predictor of bimodal benefit.

Conclusions:

• FFR F0 amplitude in the non-implanted ear is a promising objective biomarker for predicting bimodal benefit in CI users.
• FFR may facilitate data-driven clinical counseling regarding expected hearing aid and CI benefits.
• This objective measure could aid clinical decision-making, especially for difficult-to-test populations, in choosing between bimodal hearing and bilateral CI candidacy.