Phonendoscopes
There were also other types of stethoscopes designed to enhance the quality of auscultatory sounds. The most notable and widely copied stethoscope was the Phonendoscope developed by Bazzi and Bianchi in 1894. It was the first stethoscope to incorporate the use of a diaphragm membrane. The phonendoscope was small circular unit with two diaphragm membranes placed next to each other. A small steel solid rod which had a small gutta-percha chest piece was attached to the diaphragm for localization of chest and especially heart sounds. The unit could be used with or without the localizing rod. There were two long runner earpieces that attached to the top of the unit. It was totally collapsible and measured only three inches in diameter. The idea was that the small chest piece could fit between the ribs and convey better sounds. While the Phonendoscope was marketed in America exclusively by the G. Pilling Company of Philadelphia, it was made and used in many other countries.
Examples of two American Phonendoscopes made by G. Pilling & Co. On in their original velvet lined, wood box, c. 1909.
Two examples of phonendoscopes made in Europe, c. 1900. On the right is a German model with gutta percha ear pieces and on the left a similar French model with glass ear pieces. The phonendoscopes are displayed in their original, velvet lined, leather covered, carrying cases.
An interesting variation of the phonendoscope was designed by Dr. Schreiber, which could be used as either a typical monaural stethoscope or converted into a monaural phonendoscope. Schreiber's Stetheskop made of metal, circa 1900.
As shown from left to right, it could be set up as a monaural or by sliding the chest piece down the stem to expose the shaft a phonendoscope chest piece could be attached to the stem. A close up of the marked chest piece is also shown.