In general, techniques and systems for detecting acoustic signals and generating phonocardiograms are described. In one example, a system may include an acoustic sensor configured to detect an acoustic signal from a heart of a patient. The system may also include a sensing module configured to detect an electrical signal from the heart of the patient via two or more electrodes and at least one processor configured to generate a composite phonocardiogram based the acoustic signal and the electrical signal detected over a plurality of cardiac cycles of the heart, wherein the composite phonocardiogram is generated for a representative cardiac cycle. The system may be provided in a single device or multiple devices configured to transmit information between the devices.