Auditory objects typically involve motion, either because the sound source is in motion, or the listener is. Yet, most psychoacoustic research has focused on investigating sound localization for stationary sources. In normal hearing (NH) listeners, research utilizing "chimera" signals showed that envelope cues are sufficient for robust speech perception, while temporal fine-structure (TFS) cues govern binaural sound lateralization. By contrast, listeners who are deaf and use bilateral cochlear implants (BiCI) do not have access to TFS cues through clinical processors. Recent work has demonstrated poor auditory motion perception in BiCI listeners compared to NH listeners. In this study, we investigate the impact of TFS on auditory motion perception and speech understanding by simulating both stationary and moving sounds consisting of chimera-style speech and noise stimuli in virtual auditory space. Perceptual measures include speech perception, identifying whether a sound is stationary or moving, discriminating the direction of motion and explicitly reporting the absolute range of motion. The results of this study provide a baseline for measurements to be conducted with BiCI listeners. Knowledge of the cues that are not available with clinical bilateral have the potential to provide insight for improved engineering approaches for BiCIs.
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