Can measures of sound localization acuity be related to the precision of absolute location estimates?

Abstract

Studies of sound localization use relative or absolute psychoacoustic paradigms. Relative tasks assess acuity by determining the smallest angle separating two sources that subjects can discriminate, the minimum audible angle (MAA), whereas absolute tasks measure subjects' abilities to indicate sound location. It is unclear whether or how measures from the two tasks are related, though the belief that the MAA is specifically related to the precision of absolute localization is common. The present study aimed to investigate the basis of this relationship by comparing the precision of absolute location estimates with a measure of spatial acuity computed from the same data. Three cats were trained to indicate apparent sound source locations that varied in azimuth and elevation via orienting gaze shifts (combined eye and head movements). The precision of these absolute responses, as measured by their standard deviation, was compared with acuity thresholds derived from receiver operating characteristic (ROC) analyses of the cumulative distributions. Surprisingly, the acuity measures were occasionally very poor indicators of absolute localization precision. Incongruent results were attributed to errors in mean accuracy, which are disregarded in analyses of traditional relative tasks. Discussion focuses on the potential for internal biases to affect measures of localization acuity.

The acoustical bright spot and mislocalization of tones by human listeners

“…8͑a͒ is unlikely to be the result of technical error. As per Moore et al ͑2008͒, who obtained a good correspondence between identification and discrimination, values of and in Eq. ͑1͒ were taken from source-dependent behavioral data.…”

Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

“…For both cats, accuracy in localizing SS stimuli located toward the midline was more accurate (smaller error) and precise (smaller SD of error) than localizing these same stimuli at the peripheral locations. Thus the animals are both less accurate and less precise at localizing stimuli located in the periphery (see Moore et al 2008). Figure 5 shows normalized localization of PE stimuli by two cats tested with their heads free.…”

Auditory Spatial Perception: Auditory Localization

“…For example, the average error in absolute localization for a broadband sound source is about 5° for the frontal and about 20° for the lateral position Langendijk et al, 2001). Thus, it is possible that the MAA observed in these studies, where two sounds are presented in succession, and the precision of absolute localization, where only a single sound is presented, are not well correlated and measure two different human capabilities (Moore et al, 2008). This view is supported by results from animal studies, indicating that some types of lesions in the brain affect the precision of absolute localization but not the MAA (e.g., May, 2000;Young et al, 1992).…”