Nonlinear transient chirp signal modeling of the aortic and pulmonary components of the second heart sound

IEEE Trans Biomed Eng. 2000 Oct;47(10):1328-35. doi: 10.1109/10.871405.


This paper describes a new approach based on the time-frequency representation of transient nonlinear chirp signals for modeling the aortic (A2) and the pulmonary (P2) components of the second heart sound (S2). It is demonstrated that each component is a narrow-band signal with decreasing instantaneous frequency defined by its instantaneous amplitude and its instantaneous phase. Each component is also a polynomial phase signal, the instantaneous phase of which can be accurately represented by a polynomial having an order of thirty. A dechirping approach is used to obtain the instantaneous amplitude of each component while reducing the effect of the background noise. The analysis-synthesis procedure is applied to 32 isolated A2 and 32 isolated P2 components recorded in four pigs with pulmonary hypertension. The mean +/- standard deviation of the normalized root-mean-squared error (NRMSE) and the correlation coefficient (rho) between the original and the synthesized signal components were: NRMSE = 2.1 +/- 0.3% and rho = 0.97 +/- 0.02 for A2 and NRMSE = 2.52 +/- 0.5% and rho = 0.96 +/- 0.02 for P2. These results confirm that each component can be modeled as mono-component nonlinear chirp signals of short duration with energy distributions concentrated along its decreasing instantaneous frequency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aortic Valve / physiology
  • Fourier Analysis
  • Heart Sounds*
  • Humans
  • Hypertension, Pulmonary / physiopathology
  • Least-Squares Analysis
  • Pulmonary Valve / physiology
  • Signal Processing, Computer-Assisted*
  • Swine