Keywords: Recording heart sounds, microphone, low frequencies, stethoscope, recording device, headphones, piezoelectric buzzer or transducer, contact microphone, condenser microphone, electret microphone, chest piece, diaphragm, acoustic stethoscope, low frequency sounds, high frequency, beating heart, shutting heart valves, diagnostic purposes, auscultation. Healthy adults, S1 and S2 heart sounds, atrioventricular valves, mitral or bicuspid valve, tricuspid valve, semilunar valves, aortic and pulmonary valves. Hearing locations are labelled with M (Mitral), T (Tricuspid), A (Aortic), P (Pulmonic) and E (Erb’s point, the best for S2 auscultation). Stethoscope head, electronic stethoscope, waveform, recorded sound. Spectrogram, spectrum of frequencies vs. time. Amplitude is represented by the color of the image. Free Thinklabs Phonocardiography powered by Audacity software. TranslatorsCafe.com, technical English, Russian accent.