Kraman Steve S, Wodicka George R, Pressler Gary A, Pasterkamp Hans
Department of Internal Medicine, Univ. of Kentucky, Kentucky Clinic L-547, Lexington, KY 40536, USA.
J Appl Physiol (1985). 2006 Aug;101(2):469-76. doi: 10.1152/japplphysiol.00273.2006. Epub 2006 Apr 20.
Sensors used for lung sound research are generally designed by the investigators or adapted from devices used in related fields. Their relative characteristics have never been defined. We employed an artificial chest wall with a viscoelastic surface and a white noise signal generator as a stable source of sound to compare the frequency response and pulse waveform reproduction of a selection of devices used for lung sound research. We used spectral estimation techniques to determine frequency response and cross-correlation of pulses to determine pulse shape fidelity. The sensors evaluated were the Siemens EMT 25 C accelerometer (Siemens); PPG 201 accelerometer (PPG); Sony ECM-T150 electret condenser microphone with air coupler (air coupler; with cylindrical air chambers of 5-, 10-, and 15-mm diameter and conical air chamber of 10-mm diameter); Littman classic stethoscope head (Littman) connected to an electret condenser microphone; and the Andries Tek (Andries) electronic stethoscope. We found that the size and shape of the air coupler chamber to have no important effect on the detected sound. The Siemens, air coupler, and Littman performed similarly with relatively flat frequency responses from 200 to 1,200 Hz. The PPG had the broadest frequency response, with useful sensitivity extending to 4,000 Hz. The Andries' frequency response was the poorest above 1,000 Hz. Accuracy in reproducing pulses roughly corresponded with the high-frequency sensitivity of the sensors. We conclude that there are important differences among commonly used lung sound sensors that have to be defined to allow the comparison of data from different laboratories.
用于肺部声音研究的传感器通常由研究人员自行设计，或改编自相关领域使用的设备。其相对特性从未被定义过。我们使用具有粘弹性表面的人工胸壁和白噪声信号发生器作为稳定的声源，以比较一系列用于肺部声音研究的设备的频率响应和脉冲波形再现情况。我们使用频谱估计技术来确定频率响应，并通过脉冲的互相关来确定脉冲形状保真度。所评估的传感器包括西门子EMT 25 C加速度计（西门子）；PPG 201加速度计（PPG）；带有空气耦合器的索尼ECM-T150驻极体电容式麦克风（空气耦合器；具有直径为5毫米、10毫米和15毫米的圆柱形气室以及直径为10毫米的锥形气室）；连接到驻极体电容式麦克风的 Littman经典听诊探头（Littman）；以及安德里斯泰克（Andries）电子听诊器。我们发现空气耦合器腔室的大小和形状对检测到的声音没有重要影响。西门子、空气耦合器和Littman的表现相似，在200至1200赫兹范围内具有相对平坦的频率响应。PPG的频率响应最宽，有用灵敏度延伸至4000赫兹。安德里斯在1000赫兹以上的频率响应最差。脉冲再现的准确性大致与传感器的高频灵敏度相对应。我们得出结论，常用的肺部声音传感器之间存在重要差异，必须加以定义才能比较不同实验室的数据。
