Murphy R L, Holford S K, Knowler W C
N Engl J Med. 1977 Apr 28;296(17):968-71. doi: 10.1056/NEJM197704282961704.
To characterize lung sounds objectively, we examined, by means of time-amplitude plots, selected tape recordings of auscultatory phenomena considered by six observers to be typical of those in a standard classification. Normal lung sounds could not consistently be visually distinguished from adventitious sounds at conventional chart recorder speeds of 100 mm per second or less, but the differentiation was easily achieved when the time scale of the plots was raised to 800 mm per second. When discontinuous sounds (rales, crackles or crepitations) were heard clinically, the time-expanded wave forms showed intermittent "discontinuous" deflections usually less than 10 msec in duration. When continuous sounds (rhonchi or wheezes) were heard, the deflections were usually more than 250 msec. Time-expanded wave form analysis provides reproducible visual displays that allow documentation of the differentiating features of lung sounds and enhances the diagnostic utility of the sounds.
为了客观地描述肺部声音，我们通过时间-振幅图，对六名观察者认为是标准分类中典型听诊现象的选定录音进行了检查。在传统图表记录仪每秒100毫米或更低的速度下，正常肺部声音无法始终如一地从附加音中视觉区分出来，但当图的时间尺度提高到每秒800毫米时，这种区分很容易实现。当临床上听到不连续声音（啰音、细湿啰音或捻发音）时，时间扩展波形显示出间歇性的“不连续”偏转，持续时间通常小于10毫秒。当听到连续声音（哮鸣音或喘息声）时，偏转通常超过250毫秒。时间扩展波形分析提供了可重复的视觉显示，允许记录肺部声音的鉴别特征，并增强了声音的诊断效用。
