Sensitivity to binaural timing in bilateral cochlear implant users.

Area of Science:

• Auditory Neuroscience
• Neuroscience
• Audiology

Background:

• Bilateral cochlear implants (CIs) aim to restore hearing by electrically stimulating the auditory nerve.
• Interaural time delay (ITD) sensitivity is crucial for sound localization and speech understanding in noisy environments.
• Understanding ITD perception in CI users at various stimulation parameters is vital for optimizing device performance.

Purpose of the Study:

• To investigate the impact of stimulation parameters on binaural timing sensitivity in bilateral cochlear implant users.
• To compare interaural time delay (ITD) sensitivity with monaural rate discrimination.
• To explore the perception of dynamic ITD cues using binaural beats and two-pulse stimuli.

Main Methods:

• Binaural timing sensitivity was assessed in three bilateral cochlear implant users using various measures.
• Stimulation parameters included different pulse rates (100-6000 pulses-per-second), levels, durations, and modulation frequencies.
• Monaural rate-discrimination thresholds and sensitivity to binaural beats were also measured.

Main Results:

• Interaural time delay (ITD) thresholds generally increased with higher pulse rates, lower levels, and shorter durations.
• Monaural rate discrimination showed more significant degradation than ITD sensitivity as pulse rate increased.
• Sensitivity to dynamic ITD cues (binaural beats, two-pulse stimuli) was impaired at higher pulse rates and shorter inter-pulse intervals.

Conclusions:

• Bilateral cochlear implant users' ability to perceive interaural time delays (ITDs) is affected by stimulation parameters, particularly pulse rate and temporal variations.
• Dynamic ITD perception is more vulnerable to changes in stimulation parameters than static ITD sensitivity.
• Findings suggest limitations in processing time-varying binaural cues at higher pulse rates, impacting sound localization and speech perception in CI users.