Effects of monaural sound stimulation on subjective visual vertical.

Abstract

Sound stimulation can influence electrophysiological vestibular reflexes. However, the effects of sound stimulation on space perception remain unknown. To know the effects of monaural sound stimulation on subjective visual vertical (SVV). We measured SVV with and without monaural sound stimulation (105 dB, 500 Hz short tone burst presented at 4.7 Hz) in 50 healthy volunteers (aged 20-77 [mean = 42.7] years). The mean SVV was deviated 0.139° to the left by right monaural sound stimulation and 0.123° to the right by left monaural sound stimulation. SVV changes due to right and left ear stimulations were significantly different (p = 0.019). Sound stimulation resulted in a significant change in SVV on the left side (p = 0.014) in participants aged 50 or younger (mean = 35.6 years) (n = 37). This study is the first to show the possibility that the monaural sound input deviates the SVV toward the opposite side and is more pronounced for left-ear input. The vestibular-evoked myogenic potential responses may be involved in the mechanism of the contralateral SVV deviation due to sound input.