The primal role of the vestibular system in determining musical rhythm.

Previous studies have indicated that physical movement on either every second or on every third beat of an unaccented auditory rhythm pattern can disambiguate whether it is perceived in double time as a march or in triple time as a waltz. Here we demonstrate that this disambiguation can also be accomplished by direct galvanic stimulation of the vestibular system. The galvanically induced sensation, without any actual movement, that the head moved from side to side on either every second or on every third beat of the ambiguous auditory rhythm pattern strongly biased whether adults perceived it as being in double or in triple time. These results imply that the vestibular system plays a primal role in the perception of musical rhythm.