Asymmetric temporal envelope sensitivity: Within- and across-ear envelope comparisons in listeners with bilateral...

Area of Science:

• Auditory Neuroscience
• Biomedical Engineering
• Speech Perception

Background:

• Bilateral cochlear implants (BiCIs) can present degraded temporal envelope information due to patient-specific electrode-nerve interfaces.
• This degradation impacts the ability to differentiate target sounds from background noise.
• The effect of comparing degraded temporal information across spectral channels on amplitude modulation (AM) rate detection remains unclear.

Purpose of the Study:

• To investigate how comparisons of temporal envelope information across spectral channels (electrodes) influence the detection of amplitude modulation (AM) rate differences in individuals with BiCIs.
• To determine the optimal electrode pairing strategies for enhancing temporal envelope processing.

Main Methods:

• Simultaneous presentation of two pulse trains with identical or differing AM rates via electrode pairs.
• Stimuli were delivered to electrodes at different stimulation sites, within and/or across ears.
• Sensitivity to AM rate differences was measured in 11 adults with BiCIs.

Main Results:

• Sensitivity to AM rate differences was highest when stimuli were paired between different stimulation sites within the same ear.
• Electrode pair sensitivity was predicted by the performance of the poorer electrode or the fidelity difference between electrodes.
• Poorer temporal fidelity in electrodes acts as a bottleneck for temporal information comparison.

Conclusions:

• The location of electrode pairs significantly impacts the ability to detect temporal envelope differences.
• Individual electrode performance and inter-electrode fidelity differences are critical factors in auditory perception with BiCIs.
• Findings have implications for cochlear implant device programming and optimizing auditory rehabilitation.