Abstract: A medical device includes an acoustic transducer, which is configured to sense acoustic waves emitted from a body of a living subject in response to a periodic physiological activity and to output an electrical signal in response to the sensed waves. Processing circuitry is configured to compute respective autocorrelations of the electrical signal for a plurality of different times within a period of the physiological activity, to transform the respective autocorrelations to a frequency domain, and to render to a display, responsively to the transformed autocorrelations, a graphical representation of a spectral distribution of an energy of the acoustic waves over the period.

Abstract: A medical device includes an acoustic transducer, which is configured to sense infrasonic waves emitted from a body of a living subject with a periodicity determined by a periodic physiological activity and to output an electrical signal in response to the sensed waves. At least one speaker is configured to output audible sounds in response to an electrical input. Processing circuitry is configured to process the electrical signal so as to generate a frequency-stretched signal in which infrasonic frequency components of the electrical input are shifted to audible frequencies while preserving the periodicity of the periodic physiological activity in the frequency-stretched signal, and to input the frequency-stretched signal to the at least one speaker.

Abstract: A medical device (20) includes a case (32), having a front surface that is configured to be brought into contact with a body of the living subject (24). A microphone (34) is contained in the case and configured to sense acoustic waves emitted from the body and to output an acoustic signal in response thereto. A proximity sensor (56) is configured to output a proximity signal indicative of contact between the front surface and the body. At least one speaker (49) is configured to output audible sounds. Processing circuitry (50) is coupled to detect, in response to the proximity signal, that the front surface is in contact with the body, and in response to the detected contact, to process the acoustic signal so as to generate an audio output and to convey the audio output to the at least one speaker.

Abstract: A medical device includes an acoustic transducer, which is configured to sense infrasonic waves emitted from a body of a living subject with a periodicity determined by a periodic physiological activity and to output an electrical signal in response to the sensed waves. At least one speaker is configured to output audible sounds in response to an electrical input. Processing circuitry is configured to process the electrical signal so as to generate a frequency-stretched signal in which infrasonic frequency components of the electrical input are shifted to audible frequencies while preserving the periodicity of the periodic physiological activity in the frequency-stretched signal, and to input the frequency-stretched signal to the at least one speaker.