| 摘要 |
<p>DIFFERENTIAL STETHOSCOPE A portable differential stethoscope includes small microphone elements which are attached to the stethoscope heads to pick up acoustic signals from the body. The sounds picked up by the stethoscope heads include body noise signals as well as heartbeat signals. Each stethoscope head and microphone element provides an ouput which is amplified in an individual amplifier. The two amplified signals are inputted to separate terminals of a differential amplifier through a gain and balance control element. The differential amplifier ouputs a difference signal which is amplified and inputted to an electrical headset or an electrical earphone element which is acoustically coupled to the conventional acoustic tube.</p> |
