Baughman R P, Loudon R G
Am Rev Respir Dis. 1986 Jul;134(1):167-9. doi: 10.1164/arrd.1986.134.1.167.
There is a change in voice-generated sound heard over an area of pulmonary consolidation described as the "e" to "a" change. The lung may act as a low pass filter with properties that are changed by consolidation. We studied 5 patients with pneumonia. Using an electronic stethoscope, we recorded the voice-generated sounds "e" and "9-9-9." Sound spectral analysis using the fast Fourier transformation technique was used to characterize the frequency spectrum of the recorded sound. This technique allowed us to evaluate the filter properties of the normal and consolidated lung. We found that the normal lung allowed transmission of sound as high as 250 Hz with a gradual cutoff by 400 Hz. The consolidated lung allowed transmission of sound of a higher frequency; however, there was no significant transmission of sound with a frequency higher than 1,000 Hz.
在肺部实变区域听到的语音产生的声音有变化，被描述为从“e”音到“a”音的变化。肺可能起到一个低通滤波器的作用，其特性会因实变而改变。我们研究了5例肺炎患者。使用电子听诊器，我们记录了语音产生的声音“e”和“9 - 9 - 9”。采用快速傅里叶变换技术进行声音频谱分析，以表征所记录声音的频谱。这项技术使我们能够评估正常肺和实变肺的滤波特性。我们发现，正常肺允许高达250赫兹的声音传输，在400赫兹时逐渐截止。实变肺允许更高频率的声音传输；然而，频率高于1000赫兹的声音没有明显传输。
