Evening star., 1936-03-28
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

How vibrations in the air become words
and music in the brain is few steps
nearer solution as result Of experiments
reported before the American Physiologi-
cal Society here today.
First. according to report by DR. S. S.
Stevens of Harvard University, the vibra-
tions must be transformed into minute
electric currents flowing from the ears
to the auditory centers of the cerebral
corteX. They must stimulate certain fine
hair-capped cells in the inner ear. the
stimulation starting up the electrical
potential.
DR.. Stevens found by exact measure
ment that the weakest sound which can
generate an electrical potential is also
the weakest sound the ear can hear. He
also found that equal magnitudes of elec-
trical potential are generated by tones
of equal frequency and intensity and
which sound equally loud to human
observers. Furthermore. his experiments
showed the size of the electrical potential
at a constant frequency has the same
relation to the intensity of the stimulus
as it does to the subjectively estimated
loudness of the tone.
Evidence that the ear operates some
what like set of piano strings, with each
string responding to its own frequency
was offered by Drs. Edmund p. Fowler,
jr., and T. w. Forbes of Columbia Uni
versity. They also presented an explana-
ton for certain forms of deafness. such
as that found in elderly persons, or per-
sons suffering from boiler maker" deaf
ness or various types of drug poisoning.
They placed electrolytic solutions, such
as sodium ard calcium chloride, on the
thin membrane called the round win
dow" in the middle ear of an anesthetized
cat. 1t was found that these destroy the
minute electrical potentials which occur
in the inner ear and in the auditory
nerve when a sound is produced. These
potentials can be measured precisely by
electrodes.
The solutions first affected the tones
of high pitch, but as the electro
lytic agents reached further into the in
ner ear they affected lower and lower
tones. It appears as If one string after
another was put out of working order.
On microscopic examination of the ears
it was found that the hair cells which
pick up the vibrations and turn them
into electric currents were partially or
totally destroyed. The destruction re-
sembled that found in the ears OF per.
sons with 'boilermaker" deafness. -,
These two experiments, 1t was stressed
before the Psychologists, almost prove the
assumption that the electric potentials
and hearings are the same thing. DR..
Fowler and DIR. Forbes, however, are go
ing one step further to determine
whether animals in whose auditory
nerves no electric currents can be de-
tected actually are deaf. To learn this
they are using conditioned reflex" ex-
periments with animals whose nervous
systems have been SO conditioned that
they will secrete saliva at the sound OF
bell Just as they would secrete it at the
sight or odor Of food.
Existence of safety factor" in hear
ing which was described as "in accord
with good engineering practice" was re-
ported to the psychologists by DR.. Elmer
Cutler Of the University of Illinois.
From the cochlea, or sound reception
organ, In each ear nerve fibers lead to
each side Of the brain. DR.. Cutler. ex-
perimenttng with cats. first removed the