224 
PHYSIOLOGY: J. P. MINTON 
Proc. N. A. S. 
To show the ability of the person to check the data the dotted curves, 
taken six months later, are shown in figures 3 and 5. The curves 
not only check the earlier data but also show in the best possible manner 
that there has been no change to speak of during the six months' period. 
Several curves of this type have been obtained for different patients, 
but with the depressions showing up at different frequencies. We may 
ask how is it possible for so serious a defect to affect the hearing in only 
a single region of this sort? Without going into the anatomical evidence 
regarding the structure of the ear, we may say that physically the affected 
parts in these cases are evidently very loosely coupled (speaking mechani- 
cally) to the rest of the ear which functions normally out side of this region. 
Such would not be the case for middle ear trouble as shown by figures 2 
and 4. The limit of audibility for this patient, who is 25 years old, is 
about 12000 cycles which is lower than we should expect for a person of 
this age. So that, the whole region above 3000 cycles (roughly speaking) 
is probably affected. From arguments to be presented elsewhere 2 it 
may be that this lesion is one affecting the transverse fibres of the basilar 
membrane. The data at hand seem to indicate that these fibres function 
in somewhat the same way as postulated by Helmholtz and others (not 
however as pitch ' 'determinators. ") Hence, possibly the fibres above 3000 
cycles are prevented from performing their proper function while those below 
this frequency are not yet affected. 
Auditory Nerve Endings. — In concluding this brief account it is worth 
while to show how the data suggest the part played by the nerve endings, 
not as organs for changing mechanical energy into auditory nerve energy, 
but as organs which respond only to a very narrow range of frequencies 
where the pitch discrimination is good and which respond to wider ranges 
where the discrimination is not so good. Some curves were taken 
which showed that within a range of one hundred cycles the hearing 
decreased suddenly so that the patients were unable to hear even though the 
vibrational energy of the receiver diaphragm was made 10,000 times as 
great as was necessary for them to hear at the lower frequency and perhaps 
10 10 as large as was required for a normal ear to hear at the frequency in 
question. With this amount of energy the region of the internal ear 
corresponding to the lower frequency was certainly vibrating with an 
amplitude considerably in excess of that necessary for audibility. Yet, 
no tone was heard. In other words, apparently it would be necessary 
to stimulate the nerve corresponding to the higher frequency if the tone 
of the higher pitch is to be heard. So that, apparently a nerve will re- 
spond only to one frequency or a very narrow band of frequencies. The 
actual pitch determination, then, resides in the nerve endings which 
appear to have this highly selective action. It seems probable, then, 
that this work is leading into fields which can be explored by precise 
