[Heart sound measurement and analysis system with a stethoscope]

This paper is composed with the cardiac sound measurement and analysis system for in-home use of heart abnormality monitoring. The heart sound acquiring system is composed of a traditional chest-piece, earphone, microphone, and IC recorder. The recorded data is transmitted to a computer by USB interface for analysis based on the cardiac sound characteristic waveform (CSCW) method, which is extracted from an analytical model of single degree-of-freedom (SDOF). Furthermore, the characteristic parameters [T1, T2, T11, T12] are defined by the time intervals between the crossed points of the CSCW and a threshold value (THV), which are related to the first sound and the second sound and are used for discriminating normal and abnormal heart sounds. Also, an easy-understanding graphical representation for these parameters is considered, so that, even for an inexperienced user, he or she is able to monitor his or her cardiac status easily. Finally, a case study on the abnormal/normal cardiac sounds is demonstrated to validate the usefulness and efficiency of this proposed system and the cardiac sound characteristic waveform method.