Electronic stethoscope with wireless communication to a smart-phone, including a signal filtering and segmentation algorithm of digital phonocardiography signals

Abstract

This paper describes the construction of an electronic stethoscope prototype, able to amplify and filter several sounds in order to obtain heart sounds captured by a microphone attached to a conventional stethoscope chest piece, using the diaphragm; sending wirelessly, over Bluetooth, this data to an android smartphone app, capable to play and plot the sound, acting as a Phonocardiogram(PCG); and parallel, the development of a software designed to denoise sound signals through Wavelet Filters, in order to migrate this algorithm to the phone app. We obtained an acceptable sound acquisition to identify cardiac activity, however, without an optimum audio fidelity and contaminated signals due to noise addition in the wireless transmission to the phone. On the other hand the development of the signal processing is divided on 3 main steps: the fist one is the normalization of the signal, the second is the PCG denoising and the last one is the identification of different sounds with the envelope. We obtain the peaks of the normal heart sounds, base for the sound segmentation. This project must continue under research in order to improve transmission quality, and adaptation of filtering software into the app, moreover, integrate to the developed software a comparison algorithm for the detection of pathologies and achieve an application of suggested diagnosis, as final target of this investigation on long term.