Absolute vs Acoustic Standardization in Electrostethography and the Need for Studying Cardiac Vibrations As Transients

The marked variations in the audiograms of the individuals and the wide variation in frequency response of different flexible stethoscopes preclude the possibility of any widespread system of standardization. Phonocardiography has well recognized teaching and clinical value but is limited in usefulness as a clinical tool. Electrostethography eliminates the use of auditory recordings and is a direct measure of vibrations and can be easily calibrated in absolute, i.e., cgs units. The patterns produced have a gross resemblance to phonocardiographic patterns but provide measurable frequency and amplitude data. The many factors which affect heart vibrations together with the numerous types of artefacts that can occur suggest the electrostethograms should not be studied according to the techniques developed from electrocardiography but should be done with long records, multifrequency channels, and calibrated amplifiers. This method is further improved by studying the vibrations as transients on a cv scope with locked sweep and provisions for recording of selected single cycles.