Spatial hearing with interaural level differences in cochlear-implant users Over the past four decades, multi-channel cochlear implants (CIs) or bionic auditory prostheses, have been provided to severe-to-profoundly hearing-impaired individuals with the primary goal of partially restore speech understanding. There has been great success in achieving this goal – at least in quiet. More recently, CIs have been given to people with the goal to also provide access to sound in both ears, thus potentially improving spatial hearing. There remains, however, much room for improvement in sound localization abilities and speech understanding in noise in CI users. A major reason that this happens is that normal-hearing (NH) humans primarily use low-frequency (<1500 Hz) interaural time differences (ITDs) for spatial hearing; the current generation of CIs do not convey low-frequency ITDs and CI users are forced to use high-frequency interaural level differences (ILDs) for spatial hearing. Unfortunately, ILDs produced by the head are complicated functions, and it is unknown how the brain processes ILDs in the absence of ITD information. Furthermore, ILDs are distorted at multiple stages of electric sound encoding, further obscuring understanding of the encoding of spatial information with CIs. Therefore, recent work from our lab has focused on understanding ILD processing in CI and NH listeners. The goal is deeper understanding of the limitations of ILD processing for CI users and to determine if good spatial hearing can be achieved with ILDs alone, or if low-frequency ITD encoding is necessary. University of Maryland – College Park