Radio age research, manufacturing, communications, broadcasting, television (1941)

RCA DEVELOPS STETHOSCOPE Hiijlily ScMsitiue liistrnnieiit Introdiict'S Many Sounds of the Human Bodij Doctors Huue Never Been Able to Hear^Claritij and Ranqe Increased AXKW acdustic stethoscdpt' lias been developed in RCA Labo- ratories so sensitive in its range of hearing that it introduces many sounds doctors have never heard. In much the same way that the RCA Electron Microscope is open- ing unseen worlds in the submicro- scopic realm, this stethoscope, de- veloped by Dr. Harry F. Olson, promises to widen the study of sound within the human body. The beat of the heart, normal or ab- normal, respiratory rattles, peri- staltic squeaks, m u r m u r s and groans, all are amplified to facili- tate diagnosis, based upon the structure of sound. It has been found that the sounds of the body range from 40 to 4,000 cycles, the full range of which are covered for the first time by the new stethoscope. Above 4,000 cycles most of the sounds in the body are so weak that they are masked by the ambient random noises gener- ated within the body. It is ex- plained that respiratory sounds such as wheezes and the rushing of air are of a complex nature. There- fore, in designing the new stetho- scope to gain maximum intelligence the instrument transmits all fre- quencies over the range from 40 to 4,000 cycles without attenuation or discrimination. The ordinary steth- oscope has an effective range be- tween 200 and 1,500 cycles. The advantages of the new steth- oscope, according to Dr. Olson, come from the fact that it couples the ears of the diagnostician much more closely to the human body through the employment of a re- versed taper tube which results in greatly improved matching of the acoustic elements. Thus, sounds produced by the organs of the body are heard more clearly and their range is greatly widened. In fact, so many new sounds are heard with the instrument. Dr. Olson said, that a filter is built into it to enable the user, by simply turning a knob, to limit the range at will. This was done at the sug- gestion of one of the testing physi- cians in order to prevent confusion until the meaning of the new sounds can be determined through further study. It also makes the stetho- scope a more flexible tool of the doctor. In discussing the practical ap- plication of the acoustic stetho- scope, Dr. Olson pointed out that the conventional type of instrument is not effective with the lower sound frequencies of the heart or with the higher frequencies pro- duced in the chest. The new steth- oscope is expected to be invaluable by making these frequencies avail- able to the physician. "By the application of modern acoustic principles, the new steth- oscope has been developed in which the disadvantages of existing steth- oscopes have been eliminated," said Dr. Olson. "As a result, the per- formance of the new stethoscope is far superior to existing instru- ments." Detection of weak sounds by means of an ordinary stethoscope is limited, according to Dr. Olson, by the presence of noise which blankets the desired sound. "For the most part," he said, "such ex- traneous sounds are caused by the movement of clothing, and room noises, most of which are air- borne. The new stethoscope is in- sensitive to air-borne noise because DR. A. D. SUMMERS, COMPANY PHYSI- CIAN, WITH THE AID OF A NURSE, TESTS THE NEW STETHOSCOPE ON ONE OF THE RCA LABORATORIES EMPLOYEES. DR. HAKltV V. OLSON, LLFT, E.XI'LAINS TO II. D. BENSON, LABORATORY TECHNICIAN, THE PRINCIPLES OF THE NEW ACOUSTIC STETHOSCOPE. of the high mismatch between the air and the stethoscope." "The ordinary acoustic stetho- scope," Dr. Olson continued, "is one of the most useful instruments which the physician uses in medi- ate auscultation (study of body sounds by the stethoscope). By means of the stethoscope the physi- cian is able to study sounds pro- duced within the heart, lungs, stomach, intestines, or other por- tions of the body, and to determine whether normal or abnormal condi- tions exist as indicated by sounds. Obviously, it is the structure of the sound, which involves the intensity, the fundamental frequency, and the harmonic components, that makes it p(.issible to diagnose normal or abnormal conditions by ausculta- tion." The stethoscope was invented in the early years of the Nineteenth Century by a French physician, R. T. H. Laennec. Until now, there has been very little advance in its basic design. Dr. Olson has been in charge of RCA's acoustics research as related to radio, sound motion pictures, and phonograph sound pickup and reproduction for many years. He is recognized as one of the coun- try's leading authorities on acous- tics. RADIO AGE 27