Across-frequency combination of interaural time difference in bilateral cochlear implant listeners

Antje Ihlefeld*, Alan Kan, Ruth Y. Litovsky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)
7 Downloads (Pure)

Abstract

The current study examined how cochlear implant (CI) listeners combine temporally interleaved envelope-ITD information across two sites of stimulation. When two cochlear sites jointly transmit ITD information, one possibility is that CI listeners can extract the most reliable ITD cues available. As a result, ITD sensitivity would be sustained or enhanced compared to single-site stimulation. Alternatively, mutual interference across multiple sites of ITD stimulation could worsen dual-site performance compared to listening to the better of two electrode pairs. Two experiments used direct stimulation to examine how CI users can integrate ITDs across two pairs of electrodes. Experiment 1 tested ITD discrimination for two stimulation sites using 100-Hz sinusoidally modulated 1000-pps-carrier pulse trains. Experiment 2 used the same stimuli ramped with 100ms windows, as a control condition with minimized onset cues. For all stimuli, performance improved monotonically with increasing modulation depth. Results show that when CI listeners are stimulated with electrode pairs at two cochlear sites, sensitivity to ITDs was similar to that seen when only the electrode pair with better sensitivity was activated. None of the listeners showed a decrement in performance from the worse electrode pair. This could be achieved either by listening to the better electrode pair or by truly integrating the information across cochlear sites.

Original languageEnglish
Article number22
Number of pages10
JournalFrontiers in Systems Neuroscience
Volume8
DOIs
Publication statusPublished - Mar 2014
Externally publishedYes

Bibliographical note

Copyright the Publisher 2014. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • cochlear implant
  • interaural time difference
  • envelope ITD
  • across-frequency integration
  • spatial sound

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