[Audimont--a scientific research expedition to Mount Cho Oyu in the Himalayas].

Even though hearing and vestibular disorders at high altitude have been reported since 1938, their reasons are still unknown. During the Audimont Research Expedition the risk for cochlear and vestibular sensory cells has been quantified by otoacoustic emissions and videonystagmography. Vestibular disorders could not be observed up to 7050 meters. However, the outer hair cells in the inner ear showed a reduction of emissions at increasing height. The pattern of the inner ear reply, depending on the altitude, complies with an increase of the perilymphatic pressure. As the perilymphatic space corresponds directly to the subarachnoid space, the limitation of hearing thus appears to be a direct consequence of raised intracranial pressure.