Is all hearing cochlear?—revisited (again)

Abstract

Over 70 years ago John Tait raised a question with regards to the certainty that the line of division between the hearing and vestibular portions of the VIIIth cranial nerve had been drawn at the proper place [J. Tait, Ann. Otol. Rhinol. Laryngol. 41, 681–704 (1932)]. His reason for raising this question was the evidence which existed at that time that the otolith organs of anamniotes (fish and amphibians), most commonly the sacculus, were demonstrably organs of hearing in many species. He went on to speculate about a possible auditory role for the otolith organs in amniotes (reptiles, birds, and mammals), including in humans, although at this time there was no direct evidence for this. Since this time, however, there has developed a significant literature documenting evidence, not only for anamniote otolithic hearing, but also for a conserved acoustic sensitivity for the amniote otoliths. In the case of humans, this sensitivity has been exploited for the development of new acoustic tests of vestibular function. The time is ripe 70 years on, therefore, for us to revisit John Tait’s question and explore the possibility that the sacculus may indeed contribute to human hearing. [Work supported by the Royal Society.]