Gavriely N, Nissan M, Rubin A H, Cugell D W
Department of Physiology and Biophysics, Bruce Rappaport Faculty of Medicine, Rappaport Family Institute for Research in the Medical Sciences, Haifa, Israel.
Thorax. 1995 Dec;50(12):1292-300. doi: 10.1136/thx.50.12.1292.
This study was carried out to establish a reliable bank of information on the spectral characteristics of chest wall breath sounds from healthy men and women, both non-smokers and smokers.
Chest wall breath sounds from 272 men and 81 women were measured using contact acoustic sensors, amplifiers, and fast Fourier transform (FFT) based spectral analysis software. Inspiratory and expiratory sounds were picked up at three standard locations on the chest wall during breathing at flows of 1-2 l/s and analysed breath by breath in real time.
The amplitude spectrum of normal chest wall breath sounds has two linear parts in the log-log plane--low and high frequency segments--that are best characterised by their corresponding regression lines. Four parameters are needed and are sufficient for complete quantitative representation of each of the spectra: the slopes of the two regression lines plus the amplitude and frequency coordinates of their intersection. The range of slopes of the high frequency lines was -12.7 to -15.2 dB/oct during inspiration and -13.4 to -20.3 dB/oct during expiration. The frequency at which this line crossed the zero dB level--that is, the amplitude resolution threshold of the system--was designated as the maximal frequency (Fmax) which varied from 736 to 999 Hz during inspiration and from 426 to 796 Hz during expiration with higher values in women than in men. The mean (SD) regression coefficient of the high frequency line was 0.89 (0.05).
These data define the boundaries of normal chest wall breath sounds and may be used as reference for comparison with abnormal sounds.
本研究旨在建立一个可靠的信息库，记录健康男性和女性（包括非吸烟者和吸烟者）胸壁呼吸音的频谱特征。
使用接触式声学传感器、放大器和基于快速傅里叶变换（FFT）的频谱分析软件，对272名男性和81名女性的胸壁呼吸音进行测量。在呼吸频率为1-2升/秒时，于胸壁的三个标准位置采集吸气和呼气声音，并实时逐次呼吸进行分析。
正常胸壁呼吸音的振幅谱在对数-对数平面上有两个线性部分——低频段和高频段——最能通过其相应的回归线来表征。需要四个参数且足以完整定量表示每个频谱：两条回归线的斜率加上它们交点的振幅和频率坐标。高频线斜率的范围在吸气时为-12.7至-15.2 dB/倍频程，呼气时为-13.4至-20.3 dB/倍频程。这条线与0 dB水平相交的频率——即系统的振幅分辨率阈值——被指定为最大频率（Fmax），吸气时其范围为736至999 Hz，呼气时为426至796 Hz，女性的值高于男性。高频线的平均（标准差）回归系数为0.89（0.05）。
这些数据定义了正常胸壁呼吸音的边界，可作为与异常声音进行比较的参考。
