Tullio’s phenomenon. Tullio’s phenomenon corresponds to a pattern of sound-induced subjective and objective responses. The subject may feel sensations of unsteadiness, imbalance or vertigo, associated with disturbances of oculomotor and postural control. Tullio’s phenomenon is provoked by very loud sound and should be considered physiological. It is pathological if it is provoked by normal sounds. Changes to the functioning and/or the morphology of the labyrinth should be looked for in patients with the pathological form: decreased thresholds for the acoustically evoked vestibular potentials, semicircular canal dehiscence, traumatic lesions of the labyrinth, ligament hyperlaxity.