Travelling waves and tonotopicity in the inner ear: a historical and comparative perspective

In the 1940s, Georg von Békésy discovered that in the inner ear of cadavers of various vertebrates, structures responded to sound with a displacement wave that travels in a basal-to-apical direction. This historical review examines this concept and sketches its rôle and significance in the development of the research field of cochlear mechanics. It also illustrates that this concept and that of tonotopicity necessarily correlate, in that travelling waves are consequences of the existence of an ordered, longitudinal array of receptor cells tuned to systematically changing frequencies along the auditory organ.