Countless electronic stethoscopes have been developed during the past fifty years, but none has achieved any significant success. However, recent developments in small liquid crystal displays (LCDs) and advances in digital signal-processing components have rekindled interest in the possibility of developing a lightweight, portable, battery-powered instrument that would provide a visual output instead of (or in addition to) the usual audio output. This innovation could be particularly valuable to older physicians with hearing problems, as well as in facilitating the interpretation of the output signal. Direct visual display of the audio signal is not useful; rather, something more like an ECG signal, but having a greatly different spectrum and character, is desired.
