@inproceedings {Dietz1720_2016,
	year = {2016},
	author = {Dietz, Mathias and Baumgaertel, Regina and Hu, Hongmei and Williges, Ben and Kollmeier, Birger},
	title = {Extent of Lateralization with Large Interaural Time Differences in Normal Hearing Listeners and Bilateral Cochlear Implant Users},
	booktitle = {Assoc. Res. Otolaryng. MidWinter Meeting (ARO)},
	URL = {http://c.ymcdn.com/sites/www.aro.org/resource/resmgr/Abstract_Archives/UPDATED_2016_ARO_Abstract_Bo.pdf},
	abstract = {For   normal   hearing   listeners,   sound   localization   in   the   frontal  azimuthal  half-plane  is  primarily  achieved  by  neural  processing of interaural differences in level and arrival time. While  interaural  level  differences  are  to  some  extent  also  used by bilateral cochlear implant (CI) subjects, encoding of perceptually exploitable interaural time differences (ITDs) by pulse timing is still a topic of ongoing research. The current study  is  motivated  by  the  fact  that  CI  subjects  are  able  to  exploit ITDs when presented with fully synchronized low-rate pulse trains. In the first part of the study, extent of lateralization for fixed ITDs of up to 3 ms was measured in normal-hearing subjects. Stimuli were either unfiltered or 3-5 kHz band pass filtered click  trains,  the  latter  mimicking  the  perception  of  CI  users,  i.e. the absence of any low-frequency temporal fine-structure information.  Results  indicate  that,  while  unfiltered  click trains of 600 μs ITD (corresponding to almost 90° in free-field listening) were lateralized at the ear, filtered click-trains required  approximately  1.0-1.4  ms  ITD  for  equally  strong  lateralization, at least in some subjects. In  the  second  part  of  this  study,  lateralization  of  low-rate  pulse trains was measured using single electrode stimulation in  bilateral  CI  subjects.  For  the  subjects  tested  so  far  with  the  constant  rate  and  constant  level  pulse  trains,  a  change  in  lateralization  percept  with  changing  ITD  could  only  be  measured at rates lower than 200 pulses per second (pps). On average, an ITD of 1.0 ms was required to lateralize the pulse train at the ear. The   results   indicate   that,   if   the   speech   coding   allows   for  sufficiently  low  pulse  rates,  ITD  enhancement  may be  beneficial  in  future  binaural  CIs  to  provide  improved localization  performance.  The  rate  limit  of  100-200  pps  is,  however, even lower than for ITD detection. The results have inspired  the  development  of  a  signal  processing  algorithm  specific  for  binaural  CIs.  Ongoing  research  is  evaluating sound localization performance and speech intelligibility with this new algorithm.
# Funding # This work was funded by European Union under the Advancing  Binaural  Cochlear  Implant  Technology  (ABCIT)  grant agreement (No. 304912) and by the DFG Cluster of Excellence Hearing4all.}
}