The auditory subjective vertical as a function of body tilt.

A loudspeaker is moved from a position beside the subject to a position vertically above the subject's head. The subject's head is either in the normal upright position (= 0 degrees) or the head (and body) is tilted 30 degrees or 60 degrees to the left. The subject estimates the sound as vertical (=auditory subjective vertical, ASV) before it reaches the true above-head position. This results in differences between the ASV obtained from clockwise or counterclockwise movement (Fig. 1). The ASV changes with experimental time (Fig. 2). The data are discussed with respect to findings about the visually perceived SV.