Stimulus continuity is not necessary for the salience of dynamic sound localization cues.

Abstract

Correspondence between head rotation and resulting changes in interaural difference cues provides information about sound source location. We assessed whether source continuity or merely relative displacement is necessary for use of this dynamic localization cue. Low‐frequency (0.5–1 kHz) noise‐band targets, not correctly localizable in the absence of head motion or for motion duration <50 ms [Macpherson and Kerr, APCAM (2008)], were presented while the listener performed a practiced head rotation at 50 deg/s. The stimuli were either continuous (a single burst gated on and off as the head entered and exited a variable‐width spatial window) or discrete (two 20 ms endpoint bursts, triggered as the head entered and exited the window). Human listeners reported the apparent location of the stimulus by orienting with their heads subsequent to the initial head rotation. The minimum head movement angle (MHMA) necessary to resolve front/rear ambiguity was measured for each stimulus type. Similar MHMAs of 5–10 deg were measured for continuous and discrete stimuli, suggesting that endpoint “snapshots'' providing only displacement information are sufficient for use of dynamic localization cues. That parallels the finding that stimulus continuity does not improve detection of source motion [Chandler and Grantham, J. Acoust. Soc. Am. 106, 1956–1968 (1992)]. [Work supported by NSF and NIH/NIDCD.]