Tracking and time-frequency analysis on nonlinearity of tracheal sounds.

In this communication, identification of nonlinear portions in tracheal sound (TS) using third-order cumulant has been performed. The tracked nonlinearity has been then analyzed in time-frequency (TF) domain by applying a novel nonlinear analysis method based on optimally weighted Wigner-Ville distributions of the weighted subband signals from a filter bank. Similarity measurements between the optimally weighted and unweighted TF distribution outputs provide quantitative evaluation of the existence of nonlinearities. Recordings of both preprocessed as well as heart sound contaminated real recorded TS have been investigated.