The Mechanism of Audition

Abstract

IN connexion with the recent discussion in NATURE of the mechanism of the cochlea, and of the model of the cochlea designed by Mr. George Wilkinson (October 21, p. 559 ; November 11, p. 632), it seems well to point out another characteristic of hearing which will have to be taken into account in any comprehensive theory of audition. This is the abruptness of the changes which are found in the sensitivity of many ears when tested as a function of frequency. These are disclosed by the accurate determinations of the sensitivity-frequency characteristics of ears which have been made possible by the use of continuous ranges of pitch for acuity tests instead of the method of tests at discrete frequencies which has usually been used. A description of the apparatus used is given in an article soon to appear in the Physical Review. In some cases with apparently normal hearing people, changes as great as a factor of one thousand in the necessary intensity for audition are found with a change of pitch of a semitone, these occurring in connexion with depressions in the general level of sensitivity. Pictorially, this would seem to require the physical existence of a large number of elements each of which is concerned with the transmission of only a very narrow range of frequencies, these differentiated elements existing in the inner ear, in a possible cable from the ear to the brain, in the brain itself, or possibly in all three places, and of such a nature that the individual elements may be quite severely injured without seriously affecting neighbouring elements.