Free-field evoked auditory brainstem responses in cochlear implant users.

Area of Science:

• Auditory Neuroscience
• Biomedical Engineering
• Audiology

Background:

• Binaural cues are crucial for auditory stream formation and sound source segregation.
• Cochlear implants (CI) may alter interaural time differences due to processing delays, impacting binaural fusion.
• Current understanding of these effects is limited, hindering optimal binaural fitting strategies.

Purpose of the Study:

• To introduce a novel free-field auditory brainstem evoked response (ABR) analysis method for cochlear implant (CI) users.
• To investigate alterations in binaural processing caused by CI technology.
• To provide a more naturalistic assessment of ABRs in CI users by including processor delays.

Main Methods:

• Developed and applied a free-field ABR analysis technique in 12 CI users and 12 normal-hearing listeners.
• Utilized chirp and click stimuli at four different intensities.
• Analyzed both averaged (2000 trials) and single-trial ABRs.

Main Results:

• Consistent findings were observed between CI users and normal-hearing listeners in ABR amplitudes and latencies.
• Single-trial analysis revealed consistent relationships between the two groups.
• The novel method preserved intrinsic sound processor delays for natural stimulation.

Conclusions:

• The proposed free-field ABR analysis method offers a new perspective on binaural processing in CI users.
• This technique can aid future research on binaural interaction and fusion with cochlear implants.
• Understanding CI-induced alterations is key for developing improved binaural fitting strategies.