Abstract

A method and apparatus for deriving weak cardiac sounds by automatically cancelling lung sounds. The process is accomplished by providing a pair of acoustic sensors about the thorax of a patient, the first being disposed on the precordial region, adjacent to the sternum, and the second on the axillary region; obtaining sound signals from each sensor; amplifying the axillary signal by a predetermined factor; and subtracting the amplified signal from the precordial signal. An acoustic transmitter is placed on the axillary region opposite the axillary sensor. Sound waves of predetermined frequencies are emitted from the axillary transmitter to determine and compensate for phase shifts due to the electronic circuitry and the patient body. The apparatus of the present invention comprises a first acoustic sensor, a second acoustic sensor, an acoustic transmitter, a strap, transmitting cables, a processor, a cathode-ray tube, a printer, and headphones.