基于四水听器的充水弹性管声速测量方法*

实验室中水声材料声学参数的测量主要在水声声管中进行。管内平面波声速是正确测量这些参数的基础。该文提出一种基于四水听器结合不同边界的测量充水弹性管中声速的新方法。该方法利用4个固定位置处的水听器，采用最小二乘的方法，使得两组水听器分别得到的声管末端入射波声压差值的平方最小的声速即为管内平面波声速。该方法利用单频信号，在每一频率点均可测得声速，可以在任一种声管末端边界下进行测量，同时无需知道各水听器到边界的精确距离，在文中的3种边界下声速测量结果具有很好的一致性，实验操作简单、误差很小。该方法的仿真结果与管内声速的理论值吻合得很好，同时实验测量结果与仿真值之间的误差很小，证明了方法的准确性以及鲁棒性，为声管声速测量提供一个很好的思路。

Method for sound velocity measurement in a water-filled elastic tube with four hydrophones

The measurement of acoustic parameters of underwater acoustic materials in the laboratory is mainly carried out in the underwater acoustic tube, and the sound velocity of the plane wave in the tube is the basis of the correct measurement of these parameters. This paper proposes a new method for measuring the sound velocity in a water-filled elastic tube based on four hydrophones combined with different boundaries. Four hydrophones at fixed positions are adopted for this method and the least squares method is uesd. The sound velocity of the plane wave in the tube is the optimal value that can minimize the square of the difference of the sound pressure of the incident waves at the rear boundary obtained by the two groups of hydrophones. This method can measure the sound velocity at each frequency point through a single frequency signal, and the sound velocity can be measured under any boundary without knowing the precise distance from each hydrophone to the boundary. The measurement results of the sound velocity under the three boundaries in this paper are in good agreement, and the experimental operation is simple and the fluctuation of the error is small. The simulation result well conforms to the theoretical value of the sound velocity in the tube, and the error between the measurement result and the simulation result is very small, which demonstrates the accuracy and robustness of the proposed method. It provides a good reference for the sound velocity measurement in a sound tube.