Sound and postural control during stance tasks in abnormal subjective haptic vertical.

Background: Patients with vestibular impairment often suffer from postural instability. This could be compensated by other sensory systems such as the auditory system.

Objective: The aim of this study was to investigate whether auditory input improves postural stability in patients with abnormal subjective haptic vertical (SHV).

Methods: Participants (n = 13) with normal hearing and vision, but abnormal SHV participated. Participants performed standing on firm ground and foam support (eyes open/closed) and Tandem Romberg test (eyes closed) in quiet (reference), noise and with plugged ears. All tasks were conducted in a soundproofed and reverberant room. Postural stability was recorded close to the body's center of gravity. Reference conditions were compared with a control group.

Results: In only two tasks sway increased significantly when noise was presented during challenging tasks in the soundproofed room. Sway of the reference conditions did not differ significantly between control and study group.

Conclusions: This study shows no influence of applied auditory stimulation on posture in participants with abnormal SHV in a reverberant room, but an adverse effect on balance during difficult tasks in the soundproofed room. Noise possibly masked auditory information that was helpful in improving posture in the quiet condition. Futhermore, noise might have distracted participants from maintaining balance.