Binaural processing schemes for cochlear implants
Summary:
In recent years bilateral auditory input to deaf and severely hearing impaired persons has become a very important issue. Bilateral cochlear implantation (CI) is more and more common, particularly in deaf young children. Moreover, many cochlear implantees have some residual hearing in the other ear, and most of them actually using a hearing aid (HA) in that ear. At present the two systems (CI+CI or CI+HA) operate independently and real binaural effects beyond the bilateral application are difficult to demonstrate. The physical head shadow effect can clearly be resolved, but the real binaural cues (such as interaural temporal differences that normal hearing people also use for directional hearing) seem not to be ideally preserved or transmitted in the standard signal processing. This is most probably due to the independent left and right processing channels and/or to inappropriate basic electrical stimulation patterns. In this project new processing strategies will be developed that aim at representing in a better way the binaural cues in the neural responses as present in the bilateral microphone input signals.
References:
Long, C. et al. (2006): “Binaural unmasking with bilateral cochlear implants?” Journal of the Association for Research in Otolaryngology 7: 352-360.
van Hoesel, R. (2007): “Sensitivity to binaural timing in bilateral cochlear implant users”, Journal of the Acoustical Society of America 121(4):2192-2206.
Francart, T., Wouters, J. (2007): “Perception of across-frequency interaural level differences”, Journal of the Acoustical Society of America, in press.
