Computerized quality assessment of phonocardiogram signal measurement-acquisition parameters

The major focus of this study is to describe and develop a phonocardiogram (PCG) signal measurement binary quality assessment (accept-reject) technique. The proposed algorithm is composed of three major stages: preprocessing, numerical-based quality measurement and advanced measurement subroutines. The preprocessing step includes normalization, wavelet-based threshold denoising and baseline wander removal. The numerical-based quality measurement routine includes two separate stages based on energy and level of noise of the PCG signal. The advanced quality measurement step is mainly based on the interval of S1 and S2 sounds. The proposed technique was applied to 400 2-min PCG signals gathered by volunteers with range of skills in PCG data acquisition from patients with different types of valve diseases from their 2R (aortic), 2L (pulmonic), 4R (apex) and 4L (tricuspid) positions by implementing an electronic stethoscope (3M Littmann(®) 3200, 4 kHz sampling frequency). The dataset was firstly annotated manually and then, by applying the proposed algorithm, an accuracy of 95.25% was achieved.