Auditory influence on postural control during stance tasks in different acoustic conditions

BACKGROUND: Postural stability might be influenced by auditory input as humans utilize spatiotemporal information to localise sound sources. Earlier studies investigated the acoustic influence on posture but unfortunately experimental setup, room acoustics and conditions of participants varied widely. OBJECTIVE: This study aimed at recording body sway velocity under clearly defined acoustic conditions in a homogenous group of young healthy participants. METHODS: Thirty participants performed five stance tasks (standing eyes open/closed, standing on a foam support eyes open/closed, Tandem Romberg test eyes closed) under five acoustic conditions (in quiet, with a loudspeaker presenting continuous/interrupted noise, with ear protectors) in two different rooms (long/short reverberation time). Body sway velocity was determined close to body's centre of gravity. RESULTS: Postural stability decreased significantly when continuous noise was applied and increased significantly when interrupted noise was presented in the reverberant room. The usage of ear protectors increased body sway velocity compared to quietness in both rooms. CONCLUSIONS: An impaired auditory input by plugging/acoustic masking reduced postural control. Interrupted noise seems to provide a continuously repeated feedback about the postural position in a reverberant room. Hence, the effect of hearing on posture highly depends on the structure of the auditory signal, the sensorimotor condition and the acoustic environment.