A system and method for diagnosing coronary artery disease (CAD) comprises an acoustic sensor to be placed on the chest of a patient to generate acoustic signals SA: a control unit adapted to receive said acoustic signals SA, the control unit comprising: an identification unit to identify diastolic or systolic periods in a predetermined time period and to generate a period signal SP； a filtering unit adapted to apply a filter to said identified periods to generate a low frequency band signal SLFB and a high frequency band signal SHFB of said identified periods； and a calculation unit, to calculate a low frequency power measure SLFP and a high frequency feature measure SHFF. A risk-determining unit provides a risk-of-CAD signal based on the low frequency power measure and the high frequency feature measure. The invention also relates to a stethoscope and a method for detection of low frequency power.
