Article
Evidence for Context-Dependent Dilation of Auditory Space (en)
* Presenting author
Abstract:
The perceived azimuth of a sound source is biased by a preceding source (precursor), typically, towards midline (medial) by a lateral and towards the side (lateral) by a central precursor. Little is known about effects of intermediate precursor azimuths. By testing a variety of precursor and target azimuths, we studied three hypotheses regarding the precursor effect: a) binaural cue adaptation, predicting medial bias for any combination of lateral precursor and target and lateral bias for medial precursor, b) repulsion, predicting bias generally away from the precursor, regardless of spatial configuration, and c) local spatial contrast enhancement, predicting dilation of auditory space around precursor azimuth. Ten normal-hearing listeners localized 300-ms targets following 600-ms precursors using a head-pointing task in a virtual audio-visual environment. Both target and precursor azimuths were systematically varied across the azimuth range from left (-90°) to right (+90°). Stimuli were white noises, filtered with listener-specific head-related transfer functions. The data showed little evidence for hypothesis a, partial support for hypothesis b, and clear support for hypothesis c. The results are, thus, consistent with the idea that the auditory system enhances spatial contrast around the azimuth of a preceding sound and compresses contrast at remote azimuths.