The Effect of Recording Methods on the Frequency Response of Breathing Sounds Measured with an Electronic Stethoscope

The stethoscope has been used for almost two centuries mainly for listening to the lung and heart sounds. This study was conducted to characterize the frequency contents of the breathing sounds recorded with an electronic stethoscope under different conditions. These conditions included different levels of pressure applied to the probe and the use of a double-sided adhesive tape for interfacing. The goal of this study was to quantify the differences in frequency response and assess the attenuation of high and low frequencies caused by the probe-skin interface during testing. Various pressures were applied and quantified using a pressure-sensing handle developed in conjunction with this study. The signal was analyzed by using the Fast Fourier Transform (FFT) implemented in MATLAB. The data showed significant differences in frequency response with varying recording methods. The result of this study is useful for controlling the recording method when the acoustic signal from the stethoscope is used in a quantitative way.