By Arthur Kim ’18
What do a cat and a telephone have in common? They were the same thing in an experiment conducted in 1929 by Professor Ernest Glen Wever and his research assistant Charles William Bray here at Princeton University. Wever and Bray took an unconscious, but alive, cat and transformed it into a working telephone to test how sound is perceived by the auditory nerve.
To do so, they first sedated the cat and opened its skull to better access the auditory nerve. A telephone wire was attached to the nerve and the other end of the wire was connected to a telephone receiver. Bray would speak in the cat’s ears, while Wever would listen through the receiver 50 feet away in a soundproof room. The common notion during this time was that the frequency of the response of a sensory nerve is correlated to the intensity of the stimulus. In the case of the auditory nerve, as a sound becomes louder, the frequency or pitch of the sound received by the ear should be higher. When Bray made a sound with a certain frequency, Wever heard the sound from the receiver at the same frequency. As Bray increased the pitch of the sound, the frequency of the sound Wever heard also increased. This experiment proved that the frequency of the response in the auditory nerve is correlated to the frequency of the sound. To further validate their experiment, Wever and Bray performed more trials with varying conditions. When they placed the wire on other tissues and nerves away from the auditory nerve, the telephone receiver did not produce any sound. In one experiment, they restricted the blood circulation to the cat’s head, which also ceased the transmission of sound from the receiver. From their findings through these experiments, Wever and Bray were awarded the first Howard Crosby Warren Medal of Society by the Society of Experimental Psychologists in 1936.
Soon after, Bray became an Associate Professor at Princeton University and later became the Associate Research Director of the U.S. Air Force Human Resources Research. During World War II, he served as one of the leading scientists of the civilian psychological research for both the National Defense Research Council and the Navy. As for Wever, he became the head of the department of psychology at Princeton and worked with Dr. Julius Lempert of the Lempert Institute of Otology to research on otosclerosis, an abnormal bone growth in the ear that leads to hearing impairment due to the ear’s inability to amplify sound. During World War II, Wever was a consultant to the National Research Council on anti-submarine warfare. He found that men with musical abilities were the best sonar operators, regardless of what instrument they played.
Surprisingly, Wever and Bray were not particularly interested in the practical use of their discovery. Instead they cared more about the protocol and methodology to run these tests. The techniques they developed for the experiment were highly renowned by physicians who used them to study the human hearing. Their research laid a foundation for cochlear implants, devices that convert sound vibrations into electrical signals to the brain.
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For further reading:
Wever, Ernest Glen and Charles W. Bray. “Action Currents in the Auditory Nerve in Response to Acoustical Stimulation.” Proceedings of the National Academy of Science 16 (1930): 344-350.
Arthur Kim is a junior in the chemical and biological engineering department at Princeton University.