Auditory/visual distance estimation: accuracy and variability.

Paul W Anderson,Pavel Zahorik

doi:10.3389/fpsyg.2014.01097

Abstract

Past research has shown that auditory distance estimation improves when listeners are given the opportunity to see all possible sound sources when compared to no visual input. It has also been established that distance estimation is more accurate in vision than in audition. The present study investigates the degree to which auditory distance estimation is improved when matched with a congruent visual stimulus. Virtual sound sources based on binaural room impulse response (BRIR) measurements made from distances ranging from approximately 0.3 to 9.8 m in a concert hall were used as auditory stimuli. Visual stimuli were photographs taken from the participant's perspective at each distance in the impulse response measurement setup presented on a large HDTV monitor. Participants were asked to estimate egocentric distance to the sound source in each of three conditions: auditory only (A), visual only (V), and congruent auditory/visual stimuli (A+V). Each condition was presented within its own block. Sixty-two participants were tested in order to quantify the response variability inherent in auditory distance perception. Distance estimates from both the V and A+V conditions were found to be considerably more accurate and less variable than estimates from the A condition.

Highlights

Within the field of human sound localization, the perception of sound source distance has received relatively little scientific study compared to the perception of sound source direction
Generally less is known about auditory distance perception (ADP) than directional perception, it is clear that ADP results in both highly variable judgments (Zahorik et al, 2005) as well as systematic judgment biases (Zahorik, 2002a), especially when compared to directional localization performance, which is comparatively accurate and consistent (Middlebrooks and Green, 1991)
Based on independent t-tests with Bonferroni correction, the constants in the A condition (M = 2.217, SD = 1.992) were significantly greater than constants in either the V (M = 1.281, SD = 0.801) or auditory/visual stimuli (A+V) conditions (M = 1.383, SD = 0.912). These results suggest that near distances are more overestimated in the A condition than in the V or A+V condition

Summary

Introduction

Within the field of human sound localization, the perception of sound source distance has received relatively little scientific study compared to the perception of sound source direction This is surprising given that the perception of distance is at least as important as direction for conveying important spatial information about our surroundings, such as locating or avoiding auditory objects under conditions when visual information may be ineffective or unavailable. In terms of judgment bias, there appears to be general consensuses across a variety of studies and listening conditions that far distances are underestimated while closer distances are overestimated (Zahorik et al, 2005) These results are seemingly at odds with our everyday experience of auditory space that appears to be consistent and relatively accurate.

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