Improvements in Stethoscopes, Hearing Trumpets, Ear Trumpets and like Sound Conducting Instruments.

摘要

20,540. Bolte, O. Sept. 19, 1910, [Convention date]. Hearing appliances; stethoscopes. - Soundconducting instruments such as stethoscopes and ear trumpets are designed to minimize the diminution in intensity of the sound transmitted. Fig. 2 shows a stethoscope having a tube d, the walls of which are preferably hollow, which passes through the hollow stem c of a funnel a carrying a diaphragm b. The diaphragm has a central hole through which the tube d passes, the end e of the tube being adapted to enter the ear. The sound vibrations travelling up the tube cause the diaphragm to vibrate, and by means of an annular channel f between the latter and the stem c these vibrations are communicated to the ear-piece e reinforcing the sound. The tube d may be solid or the hollow shell may be filled with a soundtransmitting substance. The diaphragm and sound-reflecting surfaces of the tube and funnel may be impregnated or coated with resinous substances or metallic deposits, or with both. The ear trumpet shown in Fig. 3 has the tube d which passes through the funnel a and diaphragm b enlarged towards its outer end, the diaphragm being towards the ear. An annular space f is left at the converging end of the funnel.