A 55 year old female with idiopathic Tullio phenomenon is presented. Binocular, scleral search eye coil recordings demonstrated a predominantly torsional left-beating and vertical down-beating nystagmus in response to sound intensities over 100 dB HL to the left ear, increasing in amplitude and slow phase velocity with sound intensity and removal of visual fixation. The vertical ocular movement was conjugate, i.e. without skew deviation. Neuro-imaging, all other neuro-otological features, including ipsilateral-contralateral stapedius muscle reflexes, and surgical exploration of the middle ear, were normal. Click-evoked vestibulo-collic potentials were normal from the right ear but showed low threshold (70 dB) and increased amplitude from the left. There was no evidence that the Tullio phenomenon in this patient arises from stapes footplate hypermobility. The findings suggest that some cases of the Tullio phenomenon may be due to a hyperexcitability of the normal vestibular response to sound.