The impact of asymmetric rates on interaural time difference lateralization and auditory object formation in bilateral cochlear implant and normal hearing listeners

Abstract

Normal hearing (NH) listeners are able to accurately identify and locate sound sources using auditory object formation (AOF) and interaural time differences (ITDs). Temporal cues can further facilitate AOF and ITD sensitivity: this includes within- and across-ear stimulus’ rate, envelope-, and onset-symmetry. Bilateral cochlear implant (BiCI) listeners are not guaranteed to receive symmetrical or complementing temporal information across ears. Cochlear-Nucleus devices undergo “peak-picking” where stimulation of electrodes could yield asymmetric rates across the ears, interrupting good AOF and ITD sensitivity. We investigated the impact of asymmetric rates and ITDs, on AOF and ITD lateralization. BiCI and NH listeners were presented with diotic and dichotic pulsatile stimulus rates, combined with an ITD. Rate was fixed in one ear, and varied in the contralateral ear. In a single interval, six-alternative forced-choice task, listeners reported where and how many sounds they heard. We hypothesized that with ...