The influence of external auditory canal pressure on vestibular nerve activity was studied using guinea pigs. More than 30% of the neurons in the Scarpa's ganglion responded to the changes in the external auditory canal pressure. Most of those responsive neurons decreased their firing rates when positive pressure was applied, while they generally increased their firings when negative pressure was applied. Two out of three units in the guinea pigs whose endolymphatic duct was occluded increased their firings when positive pressure was applied.
