Longitudinal Speech Outcomes in Cochlear Implant Recipients Are Associated With Neural Factors Identified Using...

Area of Science:

• Neuroscience
• Audiology
• Biomedical Engineering

Background:

• Significant variability exists in cochlear implant (CI) recipients' speech perception abilities.
• Traditional patient history factors inadequately explain these performance differences.
• Understanding processing limitations is crucial for improving CI outcomes.

Purpose of the Study:

• To investigate the association between psychophysical and functional brain imaging measures of auditory processing limitations and long-term speech understanding in CI users.
• To identify specific limitations impacting speech perception in individuals with cochlear implants.

Main Methods:

• Forty-three CI recipients (44 ears) participated in a longitudinal study.
• Evaluated peripheral neural health via psychophysical thresholds.
• Assessed higher-order discrimination ('spectral tilt') and cortical auditory processing (functional near-infrared spectroscopy).
• Measured speech understanding in multi-talker babble noise at 1-year post-implantation.

Main Results:

• Enhanced ability to discriminate across-electrode stimulation intensities correlated with better speech understanding (R2 = 0.138, p = 0.047).
• Reduced cross-modal auditory cortex activation was linked to improved speech understanding outcomes (R2 = 0.216, p = 0.01).
• A combined regression model significantly predicted speech understanding (Adj R2 = 0.312, p = 0.009).

Conclusions:

• Psychophysical and functional brain imaging metrics significantly explain individual differences in CI speech understanding.
• Recipient-specific limitations can be identified using these measures.
• These findings support the development of personalized strategies to enhance CI speech perception.