Vol.. 8, 1922 
PHYSICS: J. P. MINTON 
279 
The concluding case to be cited was also one of pure nerve lesion due to 
pressure on the auditory nerve brought about by the growth of a cerebral 
tumor. Curve 3, figure 4, shows the relative degree of hearing possessed 
by the patient's left ear. The right ear was not greatly affected ; as shown 
by Curve 4 it required for minimum audition a relative receiver current of 
48.5 at 200 d. v. and improved with increasing pitch, requiring a relative 
receiver current of 11.5 at 5000 d. v. The curve (4) for the right ear, 
however, is almost exactly of the same shape as that (3) for the left ear. 
The lesion, then, had affected both ears alike qualitatively. In the case 
of this patient it has not been found possible to secure additional curves. 
These two cases of true nerve deafness show the maximum depression 
in hearing at the low^er frequencies, whereas for most cases of what is termed 
nerve deafness caused by lesions within the internal-ear the greatest 
depressions occur at the higher pitches. 
Many additional curves have been taken on patients with nerve deaf- 
ness, but for the purpose of the present paper it is believed that the cases 
cited are sufficient to establish the object in view. 
3. Theoretical Bearing of the Cases Cited on the Mechanical Theories of 
Tone Perception. — As stated in the introduction, it is believed that the data 
presented herewith show conclusively that the sole purpose of the me- 
chanical structure of the internal-ear is simply to lower the threshold of 
audition and that mechanical resonance of this structure is not in the 
slightest degree responsible for the phenomenon of tone perception. The 
group of curves shown in figure 3, for patients known to have internal-ears 
completely modified, showed normal pitch perception but greatly reduced 
sensitivity. If mechanical resonance of this structure were responsible 
for tone perception, then this perception would have been completely 
destroyed in these two cases. This sense remained unmodified, but the 
greatly decreased sensitivity of hearing would suggest conclusively that the 
internal-ear structure is for the prime purpose of lowering the threshold of 
audibility. 
This view is much strengthened by the group of six curves in figure 2 
for deaf-mutes all of whom showed simply reduced sensitivity of hearing 
without any apparent modification of the sense of tone perception. Among 
medical men it is considered that congenital deafness of this sort means 
that the cochlea is only partially developed. Accepting this view as even 
partially correct, we are forced to the conclusion that all theories of audi- 
tion which are based on mechanical resonance of the internal-ear are 
untenable. 
The data for Curve 1 are the same as given in figure 17 of the paper pub- 
lished in the February 1922 issue of the Physical Review, p. 88. The 
argument against the mechanical resonance theories as stated in this earlier 
paper, pp. 95-96, can be repeated here with even more decisiveness than 
