Development of New Measuring Method of Accurate Displacement and Surface Roughness by using Sound Signal

当压缩空气吹到一端关闭的小管道的开放式表面时，就会产生声音。当管道风柱的长度改变时，管道中产生的声音频率也随之改变。这一现象在本研究中得到了应用，因为物质的位移与管道中产生的声音频率相对应。本研究工作的目的是开发一种精确测量位移的新方法并将其投入实际应用。介绍了利用压缩空气产生声音的理论分析，并根据理论方程计算了探测频率。在多种测深条件下，利用压缩空气和扬声器进行了位移测量实验。通过实验数据验证了该方法的可行性。本文提出的新方法具有精度高、成本低、操作简单等特点。该方法使在极限条件下测量单位长度位移成为可能。利用上述原理，利用声频法测量了表面粗糙度，但该方法在粗糙度测量上的实践还需要进行更多的研究工作。

Sound generates when compressed air is blown onto an open-ended face of a small pipe whose one end is closed. The sound frequency generated in the pipe alter when the length of the air column of the pipe is changed. This phenomenon is applied in this research work as the displacement of the substance corresponds to the sound frequency generated in the pipe. The purpose of this research work is to develop and put to practical use a new method which is used to measure the displacement precisely.Theoretical analyses of the sound generation by suing compressed air were introduced and the sounding frequency was calculated from the theoretical equation.Experiments of the measuring displacement by using compressed air and a speaker were conducted under several sounding conditions. Experimental data were obtained to make practice of this method of the displacement.A new method described in this paper combines the features of high accuracy, low cost,simple directions ,etc. This method makes it possible to measure the displacement with a unit length under lmum.By using aboved mentioned principle, the surface roughness was measured by means of the sound frequency, however more research works are required to make practice of this method on the measuring roughness.