Ploysongsang Y, Iyer V K, Ramamoorthy P A
Department of Internal Medicine, University of Cincinnati College of Medicine, Ohio.
Respiration. 1991;58(3-4):158-62. doi: 10.1159/000195918.
Nonfiltered (NF) lung sounds from the apical area of the heart along with lung volumes and ECG signals were recorded from 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive noise cancelling (AF) [IEEE Trans. Biomed. Engng 33: 1141-1148, 1986]. The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. Five breaths from each subject were analyzed, and their spectra were similar and slightly skewed to the right. The average values of mean, median and mode frequencies of the whole breath of 5 subjects, respectively, were for NF: 64.62 +/- 3.74, 44.57 +/- 2.06 and 36.75 +/- 1.79 Hz; for 75 HF: 150.42 +/- 17.49, 114.02 +/- 6.43 and 86.16 +/- 3.13 Hz; for BL: 81.76 +/- 6.02, 52.36 +/- 2.79, 41.10 +/- 3.15 Hz; for AF: 96.87 +/- 11.58, 68.23 +/- 10.44 and 52.25 +/- 8.97 Hz. These values showed no differences between subjects. The F values obtained by the two-way analysis of variance of all breaths of all subjects (mean, median, mode) were: NF: 0.161, 0.341, 0.089; 75 HF: 0.455, 0.042, 0.085; BL: 0.108, 0.082, 0.057; AF: 0.130, 0.204, 0.113 (all p greater than 0.1). The data revealed a remarkable lack of variation within and between subjects, suggesting similar sites and mechanisms of production and transmission.
从5名正常受试者的心尖区域记录未滤波（NF）的肺音以及肺容量和心电图信号。这些信号被数字化，并采用三种心音消除方法：75赫兹高通滤波（75 HF）、心电图触发消隐（BL）和自适应噪声消除（AF）[《IEEE生物医学工程学报》33: 1141 - 1148，1986]。然后对声音信号进行快速傅里叶变换算法以获得功率谱。分析了每个受试者的五次呼吸，其频谱相似且略向右偏。5名受试者整个呼吸的平均频率、中位数频率和众数频率的平均值，对于NF分别为：64.62±3.74、44.57±2.06和36.75±1.79赫兹；对于75 HF分别为：150.42±17.49、114.02±6.43和86.16±3.13赫兹；对于BL分别为：81.76±6.02、52.36±2.79、41.10±3.15赫兹；对于AF分别为：96.87±11.58、68.23±10.44和52.25±8.97赫兹。这些值在受试者之间没有差异。通过对所有受试者所有呼吸（平均值、中位数、众数）进行双向方差分析得到的F值为：NF：0.161、0.341、0.089；75 HF：0.455、0.042、0.085；BL：0.108、0.082、0.057；AF：0.130、0.204、0.113（所有p大于0.1）。数据显示受试者内部和受试者之间明显缺乏变异性，表明产生和传播的部位及机制相似。
