254 The Structure of the Cochlea and the Perception of Tone 
of the stapes is pushed into the oval window there would result a slight 
stimulation of perhaps all the hair cells in the cochlea. The result would 
be exactly what we meet with clinically a tinnitus aurium of an indefinite 
character like the wind in the forest or the roar of a sea-shell. When a 
sudden increase or decrease in the blood-pressure results in tinnitus 
aurium the cause is the same as when the stapes is pushed into the oval 
window. The explanation for the increase or decrease of the intra- 
labyrinthine pressure is here quite evident. The tinnitus aurium arising 
from the administration of certain drugs is also plausibly explained in 
the same way as due to an alteration in the blood-supply to the labyrinth 
with resulting alteration in the pressure of the intralabyrinthine fluid. 
The tinnitus occurring in’ Menier’s disease, where there has been an 
escape of blood into the cochlea, is also similarly accounted for by this 
conception of the physiology of tone perception. The disturbances in 
the function of hearing arising from an injury produced by a shrill 
whistle or an explosion near the ear are also readily explained. In the 
first place, when a permanent disturbance in hearing is thus produced it 
can be readily accounted for by a partial severance of the relation between 
membrana tectoria and hair cells so that the hairs from a greater or 
smaller number of these cells project free in the endolymph and do not 
come in contact with the membrana tectoria and, therefore, cannot re- 
ceive the stimulation from impulses passing through the endolymph. 
On the other hand, when there results from such an injury a permanent 
tinnitus aurium, this is explained by a partial, not complete, severance 
of the membrana tectoria from hair cells over a certain area. This altera- 
tion of the relation existing normally between hair cells and membrana 
tectoria may result, as we have repeatedly pointed out, in a stimulation of 
these cells. This explanation appears all the more rational since the 
pitch of the tinnitus is often approximately that of the whistle which 
originally produced the injury. 
SUMMARY. 
1. The hair cells of the organ of Corti are the real end organs wherein 
the physical impulses of sound waves are transformed into the nerve 
impulses which result in tone perception. 
2. The perception for the various tones takes place in different parts 
of the cochlea, those of higher pitch being taken up by the hair cells 
located near the beginning of the basal coil, those of lower pitch by the 
cells near the apex of the cochlea. 
