College of Marine, Northwestern Polytechnical University, 710072 Xi'an, People's Republic of China.
J Acoust Soc Am. 2009 Dec;126(6):3049-56. doi: 10.1121/1.3242354.
The time domain implementation of the transfer-matrix method developed by Song and Bolton [J. Acoust. Soc. Am. 107, 1131-1154 (2000)] for measuring the characteristic impedance and wave number of porous materials is described in this paper. The so called Butterworth impulse is generated in a standing wave tube with a flat frequency response over a wide frequency range. With only two microphone measurements, the transfer matrix of porous layers can easily be determined through the calculation of complex amplitudes of incident, reflected, and transmitted pulses. The procedure has been used to measure the acoustical properties of a fiber material, and good agreement was found between measured acoustical properties and predicted results by Delany and Bazley [Appl. Acoust. 3, 105-116 (1971)] semiempirical formulas. Although the error associated with the sample-edge constraint still remains, the new method has a better frequency response as a result of the system calibration process, and the optimal inter-microphone distance is no longer required compared to the frequency domain implementation.
本文描述了 Song 和 Bolton [J. Acoust. Soc. Am. 107, 1131-1154 (2000)] 开发的传递矩阵法在测量多孔材料特性阻抗和波数的时域实现。所谓的 Butterworth 脉冲是在具有宽频率范围内平坦频率响应的驻波管中产生的。通过仅进行两次麦克风测量，即可通过计算入射、反射和透射脉冲的复振幅轻松确定多孔层的传递矩阵。该方法已用于测量纤维材料的声学特性，并且在测量的声学特性和 Delany 和 Bazley [Appl. Acoust. 3, 105-116 (1971)] 半经验公式预测的结果之间发现了良好的一致性。尽管仍然存在与样品边缘约束相关的误差，但由于系统校准过程，新方法具有更好的频率响应，与频域实现相比，不再需要最佳的麦克风间距离。
