Localization of noise bursts in the median plane: Effects of duration and level

Abstract

Previous research has revealed that human sound localization in the median sagittal and in the front/back dimension may depend on the listener’s ability to reliably extract information regarding characteristic peaks and notches of the source spectrum upon reaching the ears. While long-duration sounds are well localized using spectral cues, the processing of spectral cues for sounds of short duration appears to be degraded. The mechanisms involved in ‘‘image formation’’ in the localization process, and the relative importance of sound duration and level are not well understood. In the present study, the effect of signal duration and level on localization performance, with an emphasis on the median-sagittal plane were systematically explored. Three types of stimuli, clicks, noises, and trains of frozen and random noise bursts encompassing the same time period as the noises, with different duration and at various levels, were randomly presented to the loudspeakers. Subjects were blindfolded, but were instructed to move their heads as necessary, to maximize their confidence regarding source position judgment. Results will be discussed in relation to possible mechanisms employed by the auditory system to utilize spectrally shaped cues in the localization process. [Work supported by NIDCD Grant Nos. R29 DC03083 and P01 DC 00116.]