Perceptual Effects of Adaptation to Binaural Cues
* Presenting author
Neuronal adaptation affects our sound localization ability. Here, we investigated how the auditory system adapts to binaural cues using broadband stimuli containing the natural ITD- and/or ILD (interaural time and level difference) cues that exist in free-field conditions. The cues were extracted from non-individual head-related transfer functions and imposed independently on white-noise sequences. We used a spatial-discrimination experiment to investigate effects of lateral adaptors (directional cues corresponding to ±60°) and a lateralization experiment to study effects of a central adaptor. We found that the criterion for left/right discrimination becomes biased after repeated exposure to an alternating sequence consisting of an ILD adaptor on one side and an ITD adaptor on the other, potentially because the ILD adaptor affects the ILD channel tuned to that side. When similar (ITD or ILD) adaptors are used on both sides, discriminability around mid-line worsens: lateral ITD adaptors reduced sensitivity to ITD cues in the target and this effect was pronounced with ILD . On the other hand, preliminary lateralization results show that a central adaptor increases the sensitivity to binaural cues around midline. Overall, the results imply that both ITD- and ILD processing are prone to adaptation, the latter perhaps more than the former.