On the Tonotopy of the Low-Frequency Region of the Cochlea

It is generally assumed that frequency selectivity varies along the cochlea. For example, at the base of the cochlea, which is a region sensitive to high-frequency sounds, the best frequency of a cochlear location increases toward the most basal end, that is, near the stapes. Response phases also vary along cochlear locations. At any given frequency, there is a decrease in phase lag toward the stapes. This tonotopic arrangement in the cochlea was originally described by Georg von Bekesy in a seminal series of experiments on human cadavers and has been confirmed in more recent works on live laboratory animals. Nonetheless, our knowledge of tonotopy at the apex of the cochlea remains incomplete in animals with low-frequency hearing, which is relevant to human speech. The results of our experiments on guinea pig, gerbil, and chinchilla cochleas, regardless of the sex of the animal, show that responses to sound differ at locations across the apex in a pattern consistent with previous studies of the base of the cochlea.

Automated summary

This article explores the frequency selectivity and response differences in the cochlea. The results show that at the base of the cochlea, which is sensitive to high-frequency sounds, the best frequency of a cochlear location increases, and there is a decrease in phase lag towards the stapes. However, our understanding of tonotopy at the apex of the cochlea, which is relevant to human speech, is still incomplete. The experiments on guinea pig, gerbil, and chinchilla cochleas in this study demonstrate consistent response patterns across locations at the apex, similar to previous studies on the base of the cochlea.