phonocardiography

Phonocardiography is the recording and analysis of heart sounds and murmurs using a phonocardiogram, a graphical representation of the acoustic signals produced during the cardiac cycle. The primary purpose is to supplement auscultation by providing a repeatable, storable record that can be examined quantitatively and remotely.

A phonocardiogram is typically obtained with a chest-mounted sensor such as a contact microphone, piezoelectric sensor, or accelerometer, often placed at the apex or left sternal border. The signal is recorded alongside an electrocardiogram and sometimes a breath monitor. Digital processing, including filtering, is used to reduce noise from respiration, muscle activity, and ambient sounds. Sampling rates are commonly in the kilohertz range to capture rapid heart-sound events, and analyses may produce time-domain plots, spectrograms, or wavelet representations.

Interpretation focuses on the timing, relative amplitude, and morphology of heart sounds S1 and S2, the presence of additional components such as S3 or S4, and any abnormal murmurs or clicks that indicate turbulent flow or valve pathology. Phonocardiography can aid in characterizing valvular disease, congenital defects, and certain cardiac conditions, and it is sometimes used in screening, pediatric assessment, or research. However, its diagnostic specificity is limited by noise, chest-wall attenuation, and the need for expert interpretation; it is often used in conjunction with echocardiography and ECG, rather than as a standalone tool.

In recent decades, digital PCG has benefited from advanced signal processing and machine learning, enabling automated detection of murmurs and pattern recognition, though routine clinical adoption varies by setting.