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采用计算机来分析心音信号引起了越来越多的研究人员的关注,但是,心音信号在采集过程中常常会受到各种噪声的干扰,如何评价心音信号受噪声影响的程度就成为一个重要的问题。提出了一种基于循环平稳特性的心音信号噪声评价指标——质量因子,它能够准确地、定量地评估心音信号的噪声情况,即质量因子越大,信号受噪声的影响越小。如果实际采集的心音信号比较长,那么计算整个信号的质量因子,把质量因子最大的那一段心音信号取出来进行处理,这样可以大大减少去除噪声等预处理过程,节省了计算量和时间。所提出来的质量因子,对于正常和异常心音信号都适用,计算机完全可以自动计算,无需人工干预。
Computer analysis of heart sound signals has aroused more and more researchers’ attention. However, heart sound signals are often interfered by various noises during the collection process. How to evaluate the extent to which heart sound signals are affected by noise becomes an important issue . This paper proposes a quality of heart sound signal noise evaluation index based on cyclostationary characteristics, which can accurately and quantitatively evaluate the noise of heart sound signal. That is, the bigger the quality factor is, the less the signal is affected by the noise. If the actual collected heart sound signal is relatively long, calculating the quality factor of the whole signal and taking out the heart sound signal with the largest quality factor for processing can greatly reduce the pretreatment such as removing noise and save the calculation amount and time. The proposed quality factor, for normal and abnormal heart sounds signals are applicable, the computer can automatically calculate without human intervention.