The present invention relates to a system for detection of frequency power for diagnosing of coronary artery disease (CAD), comprising: an acoustic sensor adapted to be placed on the chest of a patient, and to generate acoustic signals SA； at least one memory adapted to store acoustic signals SA from the acoustic sensor； a control unit adapted to receive said acoustic signals SA； the control unit further comprises: an identification unit adapted to identify diastolic or systolic periods in a predetermined time period of the stored acoustic signals SA, and to generate a period signal Sp indicating said identified periods； a filtering unit adapted to apply at least one filter to said identified periods and to generate a low frequency band signal SLFB indicating low frequency bands of said identified periods； a calculation unit adapted to estimate the power in said low frequency band of said identified periods, to calculate a low frequency power measure based upon said estimated power and to generate a low frequency power measure signal SLFP indicating said low frequency power measure. The invention also relates to a stethoscope and a method for detection of low frequency power.
