Heart Sound Envelope Extraction Using Hilbert-Huang Transform

This article presents a comprehensive guide on implementing Hilbert-Huang Transform (HHT) for heart sound envelope extraction. The HHT method combines Empirical Mode Decomposition (EMD) and Hilbert spectral analysis to process non-stationary signals like heart sounds. Key implementation steps include: first applying EMD to decompose the signal into Intrinsic Mode Functions (IMFs), then performing Hilbert transform on each IMF to obtain instantaneous frequency and amplitude. The envelope extraction algorithm typically involves calculating the magnitude of the analytic signal generated from the Hilbert transform. Practical MATLAB implementation would require functions like 'emd' for signal decomposition and 'hilbert' for transform computation. By applying HHT, we can effectively analyze time-frequency characteristics of heart sounds and extract meaningful envelope information for clinical applications. This guide covers fundamental HHT concepts and provides detailed methodology for applying this technique to heart sound processing, offering valuable insights for researchers interested in biomedical signal analysis.