Abstract
A simple new method of recording low-frequency precordial vibrations has been presented.
(1) The pressure type transducer is deviced. The frequency response of this transducer displacement is very suitable for recording these precordial vibrations, of which frequency components usually lie between 0 and 5 cycles per second. This transducer has several special features such as a simple structure, electric stability, large electric output and good S/N ratio.
(2) The amplifier contains a condenser for the stability of the baseline and time constant becomes 2 second. Four or multi-channel electromagnetic oscillograph used is suitable for recording these vibrations with electrocardiogram, phonocardiogram or other tracings.
(3) In subsequent reports results and interpretations of patterns obtained from normal and pathologic hearts will be described.
