Heart sound propagation in the human thorax.

Simultaneous quantitative recordings of pressure in the aorta near a prosthetic valve and at two locations externally on the chest provide data on certain aspects of sound propagation in the human thorax. On the basis of the different speeds of propagation, it is possible to distinguish between the longitudinal and transverse vibrations contributing to the external phonocardiographic signal. Digital signal processing was employed to derive transfer functions, correlations and power spectra.