Abstract: Apparatus and technique for monitoring physiological parameters. An acoustic sensor or microphone is placed in close proximity to the chest of a patient having one or two prosthetic heart valves. These heart valves produce clicks characteristic of opening and closing action. The acoustic sensor picks up the sound of these clicks and transfers them as electrical energy to a transmitter unit. The transmitter unit processes the analog signal, converts it to a digital signal and establishes the key timing factors involved. This digital data is stored in a memory buffer within the transmitter. Subsequently, this information is modulated and placed on telephone lines for transmission to a central monitoring site. At the monitoring site a demodulator returns the data to baseband digital signals. A computer at the central monitoring site displays the information in the time domain and also converts the information for display in the frequency domain.