Localization performance of unilateral cochlear implant users for speech, tones and noise

Bilateral cochlear implants aim to improve sound localization compared to monaural implants, among other potential benefits. Monaural cochlear implants should not support localization in the horizontal plane as there are no interaural level and time difference cues available, although some previous studies have suggested limited capability. As background to other studies of bilateral implantation, the localization abilities of 18 monaural cochlear implantees were investigated experimentally in an anechoic chamber, using various sound stimuli with different amounts of temporal information. The effects of head movement and reverberation were also investigated. Localization performance was found to be close to chance for all stimuli. It is confirmed that monaural cochlear implants are unable to support useful auditory sound localization, even when head movements are allowed.