Coding of interaural phase differences in BiCI users

  • Stefan Zirn Department of Oto-Rhino-Laryngology of the Medical Center, University of Freiburg, Germany
  • Susan Arndt Department of Oto-Rhino-Laryngology of the Medical Center, University of Freiburg, Germany
  • Thomas Wesarg Department of Oto-Rhino-Laryngology of the Medical Center, University of Freiburg, Germany

Abstract

The ability to detect a signal masked by noise is improved in normal-hearing (NH) listeners when interaural phase differences (IPD) between the ear signals exist either in the masker or the signal. We determined the impact of different coding strategies in bilaterally implanted cochlear implant (BiCI) users with and without fine-structure coding (FSC) on masking level differences. First, binaural intelligibility level differences (BILD) were determined in NH listeners and BiCI users using their clinical speech processors. NH subjects (n=8) showed a significant mean BILD of 7.5 dB. In contrast, BiCI users (n=9) without FSC as well as with FSC revealed a barely significant mean BILD (0.4 dB respectively 0.6 dB). Second, IPD thresholds were measured in BiCI users using either their speech processors with FS4 or direct stimulation with FSC. With the latter approach, synchronized stimulation providing an interaural accuracy of stimulation timing of 1.67 µs was realized on pitch matched electrode pairs. The resulting individual IPD threshold was lower in most of the subjects with direct stimulation than with their speech processors. These outcomes indicate that some BiCI users can benefit from increased temporal precision of interaural FSC and adjusted interaural frequency-place mapping presumably resulting in improved BILD.

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Published
2015-12-15
How to Cite
ZIRN, Stefan; ARNDT, Susan; WESARG, Thomas. Coding of interaural phase differences in BiCI users. Proceedings of the International Symposium on Auditory and Audiological Research, [S.l.], v. 5, p. 341-348, dec. 2015. Available at: <https://proceedings.isaar.eu/index.php/isaarproc/article/view/2015-40>. Date accessed: 18 dec. 2017.
Section
2015/5. Compensation strategies for rehabilitation with cochlear implants