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. 2017;137(3):193-200.
doi: 10.1159/000466683. Epub 2017 Apr 26.

Development of a Smartphone App for Visualizing Heart Sounds and Murmurs

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Development of a Smartphone App for Visualizing Heart Sounds and Murmurs

Noritaka Mamorita et al. Cardiology. .

Abstract

Background: Auscultation is one of the basic techniques for the diagnosis of heart disease. However, the interpretation of heart sounds and murmurs is a highly subjective and difficult skill.

Objectives: To assist the auscultation skill at the bedside, a handy phonocardiogram was developed using a smartphone (Samsung Galaxy J, Android OS 4.4.2) and an external microphone attached to a stethoscope.

Methods and results: The Android app used Java classes, "AudioRecord," "AudioTrack," and "View," that recorded sounds, replayed sounds, and plotted sound waves, respectively. Sound waves were visualized in real-time, simultaneously replayed on the smartphone, and saved to WAV files. To confirm the availability of the app, 26 kinds of heart sounds and murmurs sounded on a human patient simulator were recorded using three different methods: a bell-type stethoscope, a diaphragm-type stethoscope, and a direct external microphone without a stethoscope. The recorded waveforms were subjectively confirmed and were found to be similar to the reference waveforms.

Conclusions: The real-time visualization of the sound waves on the smartphone may help novices to readily recognize and learn to distinguish the various heart sounds and murmurs in real-time.

Keywords: Cardiac auscultation; Heart sounds; Murmurs; Real-time sound wave visualization; Smartphone phonocardiogram app.

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