Electricity Generated in Cat's Ear Is Measured, Heard at Medical School

That certain cells in the ear of a cat generate electricity has been proved in tests conducted at the Medical School by Dr. Hallowell Davis '13, assistant professor of Physiology. It has been known since 1930 that there was electricity generated in the bodies of most mammals, but until recently it was unknown which cells produced the current.

The special cells have been isolated now, although how or why the current is generated still lies in the field of conjecture. A cat, wired to tap the current which results from the stimuli of sound waves, will convert the sound waves into current surges which can be amplified and either photographed or played over a loud-speaker.

The mechanism is a simple one. In the ear of the cat is thrust a silver wire with a damp thread on its end. Slipping past the eardrum, the thread drops into the "round window" of the cochlea. This makes one contact. The other is made by a silver plate at the base of the skull. The two wires are hooked to an amplifier and thence to a loud-speaker.

With the cat in one sound-proof room and the loud speaker in the other, any word spoken to the eat will be reproduced in electrical impulses by the cat's ear and transmitted to the speaker. Not only will the resultant words be recognizable, but it is possible to recognize the voice of the person who spoke them.

The system has been used to study the transmission of sound in the middle ear where it is beyond the range of molecular vibrations of the atmosphere. The experiment was first tried in Princeton in 1930. A turtle was used there with not very satisfactory results. The machine at the Medical School was designed for use on human beings as well as cats.

When the electrical contacts are made with a nerve, the result is quite different. A nerve is somewhat analogous to the fuse of a firecracker. When a stimulus comes, it travels up the nerve like the spark in a fuse. Just as the spark gives off light and heat, so the nerve gives off electrical disturbances. By tests of nerve stimuli, it is possible to determine the sensitivity and range of the ear.