Coding of interaural phase differences in BiCI users
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.
Colburn, H.S., Shinn-Cunningham, B., Kidd, G., Jr., and Durlach. N. (2006). “The perceptual consequences of binaural hearing,” Int. J. Audiol. Suppl., 45, S34-44.
oupell, M.J. and Litovsky, R.Y. (2015). “Sensitivity to interaural envelope correlation changes in bilateral cochlear-implant users,” J. Acoust. Soc. Am., 137, 335-349.
Goverts, S.T. and Houtgast, T. (2010). “The binaural intelligibility level difference in hearing-impaired listeners: the role of supra-threshold deficits,” J. Acoust. Soc. Am., 127, 3073-3084.
Hu, H. and Dietz, M. (2015). “Comparison of interaural electrode pairing methods: Pitch matching, ITD sensitivity and binaural interaction component,” Conference on Implantable Auditory Prostheses, Lake Tahoe, California.
Kan, A., Stoelb, C., Litovsky, R.Y., and Goupell, M.J. (2013). “Effect of mis-matched place-of-stimulation on binaural fusion and lateralization in bilateral cochlear-implant users,” J. Acoust. Soc. Am., 134, 2923-2936.
Kerber, S. and Seeber, B.U. (2012). “Sound localization in noise by normal-hearing listeners and cochlear implant users,” Ear Hearing, 33, 445-457.
Laback, B., Majdak, P., and Baumgartner, W.D. (2007). “Lateralization discrimina-tion of interaural time delays in four-pulse sequences in electric and acoustic hearing,” J. Acoust. Soc. Am., 121, 2182-2191.
Licklider, J. (1948). “The influence of interaural phase relations upon the masking speech by white noise,” J. Acoust. Soc. Am., 20, 150-159.
Moore, B.C.J. (2012). An Introduction to the Psychology of Hearing. 6th Ed., Brill.
OLSA (2011). Oldenburger Satztest. Bedienungsanleitung für den manuellen Test auf Audio-CD. http://www.hoertech.de/web/dateien/HT.OLSA_Handbuch_Rev01.0_mitUmschlag.pdf
Seeber, B.U. and Fastl, H. (2008). “Localization cues with bilateral cochlear implants,” J. Acoust. Soc. Am., 123, 1030-1042.
van Hoesel, R., Bohm, M., Pesch, J., Vandali, A., Battmer, R.D., and Lenarz, T. (2008). “Binaural speech unmasking and localization in noise with bilateral cochlear implants using envelope and fine-timing based strategies,” J. Acoust. Soc. Am., 123, 2249-2263.
Authors who publish with this journal agree to the following terms:
a. Authors retain copyright* and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
b. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
c. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
*From the 2017 issue onward. The Danavox Jubilee Foundation owns the copyright of all articles published in the 1969-2015 issues. However, authors are still allowed to share the work with an acknowledgement of the work's authorship and initial publication in this journal.