REDUCTION OF HEART SOUNDS FROM LUNG SOUNDS BY ADAPTIVE FILTERING.

Auscultation of the chest is an attractive diagnostic method owing to its simplicity and noninvasiveness, and lung sound analysis using time- and frequency-domain techniques would increase its usefulness. The sounds recorded or heard are, however, contaminated by heart sounds which interfere with the diagnosis based on an analysis of lung sounds. Filtering out the heart sounds with linear high-pass filters also eliminate the overlapping spectrum of breath sounds. It is shown how adaptive filtering can be used to reduce heart sounds without significantly affecting breath sounds. The technique reduces the unwanted heart sounds by 50-80%.