| Heart disease is one of the most important diseases in the world which seriously endangers the health of people in the world. In the recent past 10 years, with the development of living standards and life expectancy increases, the global incidence of heart disease is increasing year by year. Because of the features of severity, universality and complexity of heart disease, the demand of diagnosis and treatment to heart disease become higher. To the preventtion of heart disease, the most effective method is early diagnosis and timely treatment. Therefore, the non-destructive testing and diagnosis for heart disease prevention is very essential. Heart sound signal is one of important human physiological signals, contains a wealth of original physiological and pathological information of human heart or blood vessels. It is of great significance for the clinical diagnosis and treatment.In this paper, based on the analysis of method in heart sound signal detection and analysis, overcoming the deficiency of previous method and technology, Developing virtual heart sound signal detection and analysis system employing significant achievements in the field of signal processing, computer hardware and software technology in recent years, combined with Labview8.6, development platform as the representative of the virtual instrument technology. Especially the application of joint time-frequency, time series, wavelet transform analysis of modern digital signal-depth study of heart sound signals provide an effective tool for the early diagnosis of heart disease. This paper is related to heart sound signals time-frequency analysis method and a virtual dynamic heart sound signal detection and analysis system, achieveing following four aspect results.1. Based on JTSA (joint time-frequency analysis) of the heart sound signal analysis: the heart sound analysis which is based on the STFT(Short time Fourier transform), the integrated heart sound analysis which is based on JTSA (joint time-frequency analysis) MIF (instantaneous frequency) and analysis of heart sounds which is based on JTSA MIB (instantaneous bandwidth) analysis. According to the joint time-frequency analysis of heart sound signal, the process of frequency change over time is obtained in the time-frequency plane. Using some special transformations to highlight some special characteristics of heart sounds, as the time-frequency analysis method has a strong energy aggregation, so it is easy to get the energy map of heart sound signals through comparative analysis of the energy spectrum to achieve early diagnosis of heart related diseases.2. Based on WT (wavelet analysis) of the heart sound signal analysis: It covers the multiresolution analysis of heart sound signal based on DWT (Discrete Wavelet Transform)and CWT (continuous wavelet transform), multi-scale wavelet transform of heart sound signal analysis and energy map of heart sound signal based on wavelet-based 2D. Take full advantage of the characteristics of multi-resolution wavelet transform to extract the detailed features of heart sound signals, successfully extract the first heart sound and second heart sound, and according to the appearing time and energy feature of the first heart sound, second heart sound and other noise, normal heart sounds and abnormal heart sounds can be distinguished, and so do heart disease related heart sounds.3. Based on TSA (time series analysis) of the heart sound signal analysis: it consists of the heart sound signal analysis based on TSA, 3D analysis based on AR method and FFT method. the three-dimensional analysis of heart sounds is did by establishing AR model and fast Fourier transform method, compared normal subjects, mitral stenosis and aortic stenosis in patients with three-dimensional map of heart sound characteristics, to analyse these different types of heart sound signal characteristics by analyzing three-dimensional map of spectral peaks, the location and frequency changing characteristic in to achieve a prediction of disease-related diagnosis.4. Virtual dynamic heart sound detection and analysis system. Virtual dynamic heart sound signal detection and analysis system consists of hardware and analysis software system. Hardware is made up by the heart sound sensor, heart sound signal amplifier, computer USB interface block and computer system; analysis software system consists of Windows XP system software, Labview development software and heart sound signal analysis module which consists of kinds of subroutines. The system can complete the heart sound signal acquisition, display, review, storage, and analysis of time and frequency domain. The system is constituted simply, can be operated conveniently, and has a powerful capacity of heart sound analysis. It is an effective tool of diagnosis of heart sounds related diseases. |
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