Effect of sound and vision on balance performance

Abstract

Postural control is important to human movement and acting in daily living. Sensory systems including the visual, vestibular and proprioceptive systems are significant components of the postural control mechanism. The auditory system also appears to influence postural control. The aim of this study was to investigate the effect of sound and vision on balance performance. Fifty Thai women aged between 20 and 35 years participated in the study. Balance performance was examined by using the SMART Balance Master System. A total of 12 conditions were examined: eyes open, eyes open with sound on left ear, eyes open with sound on right ear, left eye closed, left eye closed with sound on left ear, left eye closed with sound on right ear, right eye closed, right eye closed with sound on left ear, right eye closed with sound on right ear, eyes closed, eyes closed with sound on left ear and eyes closed with sound on right ear. The parameters of the present study were the center of gravity (COG), sway excursion in the anteroposterior (AP) and the mediolateral (ML) directions, average sway velocity, the percentage of maximum stability and the percentage of ankle strategy. The results demonstrated the visual-auditory interaction inducing an increase in COG sway excursion in the AP direction and a decrease in the percentage of maximum stability. The visual feedback was more dominant than the auditory input at the left ear. Additionally, the auditory input at the right ear appeared to disturb the COG sway excursion in the AP direction when there was full visual feedback. When loss of visual feedback from both eyes or an eye occurred, postural destabilization was observed in all parameters. Moreover, the auditory input influenced postural control in the COG sway in the ML direction. In conclusion, the interaction and individual effects of the visual and the auditory inputs affect postural balance performance. It is suggested that the visual input is more dominant than the auditory input in controlling posture.