Speech Comprehension by Cochlear Implant Users Assessed with Evoked Potentials and Response Times

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Cognitive Neuroscience

Background:

• Cochlear implant (CI) rehabilitation outcomes, including speech-in-noise understanding, show significant variability among users.
• Cross-modal cortical reorganization is observed in individuals with hearing loss, but its impact with regular hearing device use is not well understood.

Purpose of the Study:

• To investigate cortical responses related to speech comprehension in experienced CI users versus normal-hearing controls.
• To explore how cross-modal cortical reorganization affects speech processing in CI users.

Main Methods:

• Multichannel electroencephalography (EEG) was used to record cortical responses (N400 and late positive complex) in 13 experienced CI users and 13 matched controls.
• Participants processed congruent and incongruent digit-triplet stimuli in auditory-only, visual-only, and visual-then-auditory modes under noisy conditions.
• Response times and EEG components were analyzed to assess comprehension abilities.

Main Results:

• No significant group differences were found in N400 and late positive complex (LPC) component amplitudes.
• Cochlear implant users exhibited slower response times compared to controls.
• Response times in CI users were differentially affected by the three stimulus presentation modes.

Conclusions:

• Experienced CI users may require more time for speech comprehension in noise compared to their normal-hearing counterparts.
• Response time serves as a reliable indicator for evaluating speech comprehension capabilities in individuals using cochlear implants.