Design And Implementation Of Lung Sound Analysis System Based On Virtual Instrument

The virtual instrument technology which was born at the end of last century is a kind of senior measurement and control technology. It fully combine computer and instruments technology, which are already widely used in various fields. Lung sound in the body is a kind of special physiological signal ,which represents characteristics of the human respiratory system. Lung sound signal is of great significance in clinical medicine research and teaching. Therefore, developing an analysis system of lung sound based on virtual instrument has a significant meaning.This system chooses the popular LabVIEW software platform, developing a set of virtual instrument which integrates mainly lung sound signal collection module, de-noising module and analysis module. Lung sound acquisition module mainly depends on piezoelectric sensors and computer sound card for the hardware. Do set the configuration parameters on the front panel such as sample rate and then the lung sound signal can be collected.Lung sound de-noising module is a characteristic module of this design system. The main frequency of lung sound concentrate in 10-250 Hz. So heart sound and other physiological signal have very big overlap with lung sound signal. Heart sound below 150 Hz , may have a significant interference which have produced major interference to lung sound. An improved method of removing heart sound has been proposed in this module. The method uses wavelet multi-scale product of coefficient of approximation to detect heart sound of the original lung sound. Once the heart sound components are recognized, they will be removed from every level of wavelet coefficients. After then, this method uses ARMA model to estimate purify part of data, compensating the results to the generated gaps. Finally the heart sound from the lung sound is removed and have not interfered to the lung sound's main ingredient.Finally, lung sound signal analysis module is effectively developed with Matlab,, including FFT spectrum and spectral analysis, wavelet analysis and Wigner-Ville analysis. The results can be used to analyze and judge all types of sick signals of lung sound.According to the experimental results, this system can collect good lung sound signal and effectively remove heart sounds and analyze the lung sound in different ways. The general effect is good, and meets expectations.