There is something even ludicrous in the picture of a gray physician proudly listening through a long tube applied to the patient's thorax. Many wooden and rubber models were tried, but none caught on until 1852, when Dr. George Cammann of New York designed a binaural stethoscope which not only transmitted more sound and blocked out extraneous sounds, but was also the first to resemble today's instruments. Early stethoscopes had only a bell chest piece. This excelled at picking up low frequency sounds, but missed many at higher frequencies. Acoustic stethoscope design culminated with the lightweight Littman model introduced in 1961, and still the mainstay of physicians and nurses.
Acoustic stethoscopes are, of course, limited in their ability to transmit and amplify sound.
This problem was addressed in 1910 by S.G. Brown in London. He invented a repeater, amplifier, and receivers that would allow transmission to 50 miles and more. And so was the first telestethoscope born. The concept languished for over fifty years. More definitive academic assessment of tele-auscultation came when Mattioli and his team began publishing their series of studies in 1992.