A RESTUDY OF THE MINUTE ANATOMY OF S'TRUCTURES 
IN THE COCHLEA WITH CONCLUSIONS BEARING 
ON THE SOLUTION OF THE PROBLEM OF TONE 
PERCEPTION. 
BY 
GEORGE E. SHAMBAUGH. 
From the Hull Laboratory of Anatomy of the University of Chicago. 
WITH: 2 PLATES. 
It is generally conceded that in the cochlea is located the mechanism 
whereby the physical phenomena of sound waves are converted into the 
nerve impulses which result in tone perception. Long ago the idea was 
suggested that this process for the several tones takes place in different 
parts of the cochlea. It remained for Helmholtz, however, to give this 
hypothesis its greatest scientific support, and in literature it is best known 
as the “ Helmholtz Theory ” or the “ resonator theory ” of tone perception. 
This theory finds a powerful support in the physiological fact that the 
organ of hearing possesses the faculty of tone analysis, a phenomenon 
that has its physical analogy in the sympathetic vibrations which take 
place in the strings of a piano forte when the corresponding tones are 
produced in another instrument. The clinical observation, too, that in 
certain cases where there has been a more or less extensive destruction 
of the function of hearing, circumscribed “ islands of hearing ” are found 
where the perception for certain tones is preserved, speaks strongly in 
favor of the presumption that the perception for the various tones takes 
place in separate and distinct parts of the cochlea. 
Anatomically, we find in the long rows of hair cells running through- 
out the entire length of the cochlea a mechanism admirably suited to the 
requirements of such a theory. These hair cells are the real end-organs, 
wherein the transference of the physical sound waves to nerve impulses 
takes place. Each cell, or rather group of cells, when adequately stimu- 
lated, leads to the perception of a particular tone. The higher tones, 
presumably, are taken up by the cells located in the basal coil, the lower 
tones by the cells near the apex of the cochlea. 
The manner in which the stimulus is applied to these hair cells and 
AMERICAN JOURNAL OF ANATOMY.—VOL. VIJ. 
