Noise and disturbance reduction for heart sounds in cycle-frequency domain based on nonlinear time scaling.
Through an investigation of various clinical cases, heart sounds are found to be quasi-cyclostationary. Nonlinear time scaling from cycle-to-cycle is proposed to enhance cyclic stationarity, where nonlinear time scaling is approximated by a piecewise linear function. The techniques of cyclostationary signal processing are employed in this paper to reduce noise and disturbance in the cycle-frequency domain. Heart sounds can be theoretically recovered in the presence of additive, zero mean noise, and disturbance (perhaps non-Gaussian, nonstationary, or colored). The experimental tests in various conditions confirm the theoretical results.
Tang
Hong
H
Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China. tanghong@dlut.edu.cn
Li
Ting
T
Qiu
Tianshuang
T
D000465:Algorithms; D004562:Electrocardiography / Q000379:methods*; D006339:Heart Rate / Q000502:physiology*; D006347:Heart Sounds / Q000502:physiology*; D006801:Humans; D017711:Nonlinear Dynamics; D016011:Normal Distribution; D012815:Signal Processing, Computer-Assisted