A survey is given of the literature on the sensitivity of the vestibular system to audio-frequency sound and vibration in animals. It is also shown that responses to such stimuli can be evoked in man. On the basis of these results it was decided to perform a fenestration of the horizontal semicircular canal in three profoundly deaf volunteers, with normal sensitivity of the vestibular system. The first results are promising: the threshold for audio-frequency vibration in the operated ears improved markedly. Furthermore, the subjects reported perception of environmental sounds using a bone conductor hearing aid.