Noise/spike detection in phonocardiogram signal as a cyclic random process with non-stationary period interval.
The major aim of this study is to describe a unified procedure for detecting noisy segments and spikes in transduced signals with a cyclic but non-stationary periodic nature. According to this procedure, the cycles of the signal (onset and offset locations) are detected. Then, the cycles are clustered into a finite number of groups based on appropriate geometrical- and frequency-based time series. Next, the median template of each time series of each cluster is calculated. Afterwards, a correlation-based technique is devised for making a comparison between a test cycle feature and the associated time series of each cluster. Finally, by applying a suitably chosen threshold for the calculated correlation values, a segment is prescribed to be either clean or noisy. As a key merit of this research, the procedure can introduce a decision support for choosing accurately orthogonal-expansion-based filtering or to remove noisy segments. In this paper, the application procedure of the proposed method is comprehensively described by applying it to phonocardiogram (PCG) signals for finding noisy cycles. The database consists of 126 records from several patients of a domestic research station acquired by a 3M Littmann(®) 3200, 4KHz sampling frequency electronic stethoscope. By implementing the noisy segments detection algorithm with this database, a sensitivity of Se=91.41% and a positive predictive value, PPV=92.86% were obtained based on physicians assessments.
Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. Hnaseri@gmx.com
H
H
Naseri
M R
MR
Homaeinezhad
H
H
Pourkhajeh
D000465:Algorithms; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D010701:Phonocardiography / Q000295:instrumentation / Q000379:methods; D012815:Signal Processing, Computer-Assisted
CFI; Cluster template; Clustering; Correlation coefficient; DM; DSR; ECG; Energy time series; Ensemble averaging; FFT; FN; FP; Fast Fourier Transform; Filtering; Filtering strategy curve; Frequency time series; GSF; Gaussian smoothing filter; Orthogonal reconstruction; PCG; PPV; PWT; SNR; SP; STFA; TN; UPE; cosine Fourier integral; detection metric; disturbance to signal ratio; electrocardiogram; false negative; false positive; packet wavelet transform; phonocardiogram; positive prediction value; short-time frequency amplifier; signal to noise ratio; specificity; true negative; uniform piecewise energy