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E\SCIENCE|2 SCIENCE FINDS AMAZING NEW USES FOR SOUND by Dr Sergius P. Grace Assistant to Vice President Bell Telephone Laboratories As told to J. Earle Miller SCIENCE FINDS AMAZING partly an electrical manifestation in NEW USES FOR SOUND which a minute current is generated by Dr Sergius P. Grace in the auditory nerve. At Princeton Assistant to Vice President University not long ago, electrical Bell Telephone Laboratories contacts were established to the As told to J. Earle Miller auditory nerve and brain of a cat, the minute current in the nerve Thanks to astounding discoveries made amplified through radio tubes, and recently in the field of sound, you will soon words spoken into the ear of the be able to talk around the world, deaf living cat in one room were mutes will hear, and communication in reproduced through loud speakers battle areas will be revolutionized. The in another. amazing inventions which make such feats At Bell Laboratories we not only possible are described in this article. ave developed special apparatus to — Modern Mechanics and Inventions make it easier for deaf people to use magazine, July 1931 the telephone, but we have also created several portable outfits, Devices to improve hearing nown as audiophones, which help na recent lecture on the new these unfortunate ones to join again [rere being developed in the in conversation with their friends. Bell Laboratories, | placed my Few people realize that there is a finger against the ear of one of the definite upper limit to the loudness members of the audience and he_ that the ear can stand, so that "heard" music and speech, though extreme cases of deafness are not a sound was audible on the beyond the aid of even the most stage. potent amplifier. That was electrostatic projection Under the guidance of Dr Harvey of speech directly into the human Fletcher we have developed the brain. The speech had been audiometer, an instrument to transformed into high-voltage measure hearing. It shows electric current [and] passed conclusively that no two cases o through my body, while the ear deafness are quite alike, and tha drum and surrounding tissue of the hearing-aid that proves successfu subject acted as one plate of a for one person may be quite condenser receiver. unsuited for another. Dr Fletcher Just a laboratory experiment, so has developed a simple method in far, yet it is one of many new which someone reads off lists o discoveries that are opening new words, at a distance of three fee leads into the field of hearing, from the pick-up device. One lis helping improve devices for the contains fifty words such as "bat", transmission of sound and bringing bite, boot, beat", in which the vowe hearing back to the deaf. It is quite is different for each; the other has possible, as some research workers fifty words in which the consonan have suggested, that science may differs, such as "by, high, thy, guy, make it practical to "hear" without why". After making this test with using the ear drum at all. several hearing aids, and scoring Hearing, it has been discovered, is errors in the consonants twice as heavily as in the vowels, the user can decide which device best suits his particular kind of deafness. The speech inverter The projection of speech direct into the brain is only one of the fantastic marvels of recent years. Every day the air is filled with trans- oceanic radio telephone messages, winging their way between New York and Europe, South America, Australia and South Africa. From any telephone in the United States you can call any telephone subscriber in those far-flung quarters of the globe, but, when you alk, no eavesdropper can listen in. Far down in lower New York, your voice passes through a speech inverter mechanism which turns it into a new language, unintelligible o the ear. With patient practice one can learn some of the inverted words, but many are sounds which he human larynx cannot master. The speech inverter is quite simple in theory. Normal telephone speech falls between vibrations of 00 cycles up to 2,900 cycles. When he speech is inverted, for every vibration is substituted a new one whose frequency is equal to some selected constant frequency, less the requency of the original sound. We use 3,000 cycles for the constant requency, and a deep bass note of 100 cycles is thus transformed into a igh soprano of 2,900 cycles, while he high notes are inverted to deep bass. The result is much like passing light through a camera lens, which inverts the image, so the top of the picture is focused on the bottom of the film in the camera and the bottom of the image appears at the top. Devices to improve hearing na recent lecture on the new [rere being developed in the Bell Laboratories, | placed my finger against the ear of one of the members of the audience and he "heard" music and speech, though not a sound was audible on the stage. That was electrostatic projection of speech directly into the human brain. The speech had been transformed into high-voltage electric current [and] passed through my body, while the ear drum and surrounding tissue of the subject acted as one plate of a condenser receiver. Just a laboratory experiment, so far, yet it is one of many new discoveries that are opening new leads into the field of hearing, helping improve devices for the transmission of sound and bringing hearing back to the deaf. It is quite possible, as some research workers have suggested, that science may make it practical to "hear" without using the ear drum at all. Hearing, it has been discovered, is It JUNE — JULY 2009 NEXUS ¢ 51 www.nexusmagazine.com