Neural encoding of spectro-temporal cues at slow and near speech-rate in cochlear implant users

Jaime Undurraga Lucero*, Lindsey Van Yper, Manohar Bance, David McAlpine, Deborah Vickers

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The ability to process rapid modulations in the spectro-temporal structure of sounds is critical for speech comprehension. For users of cochlear implants (CIs), spectral cues in speech are conveyed by differential stimulation of electrode contacts along the cochlea, and temporal cues in terms of the amplitude of stimulating electrical pulses, which track the amplitude-modulated (AM’ed) envelope of speech sounds. Whilst survival of inner-ear neurons and spread of electrical current are known factors that limit the representation of speech information in CI listeners, limitations in the neural representation of dynamic spectro-temporal cues common to speech are also likely to play a role. We assessed the ability of CI listeners to process spectro-temporal cues varying at rates typically present in human speech. Employing an auditory change complex (ACC) paradigm, and a slow (0.5Hz) alternating rate between stimulating electrodes, or different AM frequencies, to evoke a transient cortical ACC, we demonstrate that CI listeners—like normal-hearing listeners—are sensitive to transitions in the spectral- and temporal-domain. However, CI listeners showed impaired cortical responses when either spectral or temporal cues were alternated at faster, speech-like (6-7Hz), rates. Specifically, auditory change following responses—reliably obtained in normal-hearing listeners—were small or absent in CI users, indicating that cortical adaptation to alternating cues at speech-like rates is stronger under electrical stimulation. In CI listeners, temporal processing was also influenced by the polarity—behaviourally—and rate of presentation of electrical pulses—both neurally and behaviorally. Limitations in the ability to process dynamic spectro-temporal cues will likely impact speech comprehension in CI users.
Original languageEnglish
Article number108160
Pages (from-to)1-14
Number of pages14
JournalHearing Research
Volume403
Early online date30 Dec 2020
DOIs
Publication statusE-pub ahead of print - 30 Dec 2020

Fingerprint Dive into the research topics of 'Neural encoding of spectro-temporal cues at slow and near speech-rate in cochlear implant users'. Together they form a unique fingerprint.

Cite this