Electronic Stethoscope Design, Prototyping and Testing

The design, prototyping and testing of an electronic stethoscope, to auscultate internal body sounds is presented. The microphone used is an air pressure transducer. An active, 4th order, Butterworth band-pass filter is implemented with a 1 dB ripple in the passband. The system bandwidth is 20-2000 Hz with a system sampling frequency of 25600 Hz yielding an aliasing error of 31.62 %. The system offers processing which entails: analogue filtering and amplification, data logging, display of phonograms, digital filtering, denoising and feature extraction. The complete system Signal-to-Noise ratio is 110.81 dB with a total cost of R1408.39.