The Construction And Application Of Heart Sound Wavelets

Heart sound belongs to the faint biological signals under the strong background noise. It is oneof the most important physiological signals of the human body and is a complex tone generated bythe myocardium, blood, valves and the other mechanical vibrations during the diastole andcontraction of the heart. It directly reflects the mechanical movement condition of great vessels andcardiac system and also reflects the physiological and pathological information of each part of theheart. Detection and analysis of heart sound signals have a positive significance in the earlydiagnosis of cardiovascular disease. In the field of heart sound signal processing, the wavelettransform has become one of the most effective measures in preprocessing, frequency-division,decomposition and reconstruction of the signals.The selection of wavelet base is the first job when using the wavelet transform to analysis theheart sound. Generally speaking, the selected wavelet should be similar to the signal. The differentwavelet bases have different time-frequency characteristics and have different results when usingwavelet to decompose the same heart sound. A suitable wavelet base should satisfy compactlysupported, symmetry, high vanishing moments and regularity. In order to further improve theperformance of the wavelet analysis in the process of the heart sound signals, the thesis constructeda wavelet basis which is exclusively used in the process of the heart sound signals on the basis ofheart sound andwavelet theory construction. This thesis firstly proposed a general method ofconstructing a compactly supported biorthogonal wavelet which has even length filter banks;Secondly, according to the characteristics of heart sound signals, the thesis discussed the structureprinciple of heart sound wavelet and a synthesis model of heart sound signals based on the heartsound wavelets; Finally, the thesis constructed the heart sound wavelet on the basis. In order tohighlight the advanced and practical of heart sound wavelet in processing heart sound signals, thethesis analysed the theory and numerical simulation of heart sound wavelet more comprehensively.Experimental results show that, compared with the commonly used db and bior series wavelets,using the heart sound wavelet to process the heart sound signals can obtain better denoising effect、more accurate classified information of heart sound and lower reconstruction error rate. So the heartsound wavelet provided a new method in in-depth study of heart sound feature extraction andidentification and has a positive significance in describing the details of the individualcharacteristics of the heart sounds. The thesis designed a method of the special wavelet which is based on the application object providing a new approach for the selection of wavelet basis inengineering applications. It also provides a new method for the detection and manipulation of weakphysiological signals under the strong background noise.