Near real time noise detection during heart sound acquisition

Heart sound is a valuable biosignal for early detection of a large set of cardiac diseases. Ambient and physiological noise interference is one of the most usual and high probable incidents during heart sound acquisition. It tends to change the prominent and crucial characteristics of heart sound which may possess important information for heart disease diagnosis. In this paper, we propose a new method to detect ambient and internal body noises combined with heart sound. The algorithm is based upon the periodic nature of heart sounds and physiologically inspired criteria. A small segment of clean heart sound exhibiting periodicity in time as well as in the frequency domain is first detected and applied as a reference signal in sorting noise from the sound. The achieved average sensitivity and specificity are 94% and 97%, respectively.