Posturography frequency analysis of sound-evoked body sway in normal subjects.

Sound-evoked activation of the vestibular system has been suggested for a long time, and myogenic potentials have been recorded at the level of different muscular groups while a high intensity sound was applied. The aim of this study was to analyse sound-evoked postural responses in normal subjects and to correlate them with the activation of the vestibular system. Body sway was measured by posturography and elaborated through spectral frequency analysis in 40 healthy volunteers in the basal condition and after applying a sound stimulus monoaurally. Spectral frequency analysis results showed a significant increase, in presence of stimulus, of body sway at low and middle frequencies only on the lateral plane and in the closed-eyes condition. As it seems that these frequency ranges are mainly under vestibular control, our results suggest that sound activates specifically the vestibular system, and posturography during sound stimulation represents an alternative approach to assess vestibular function.