Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
Coastal Ocean Monitoring Center, National Cheng Kung University, Tainan 70101, Taiwan.
Sensors (Basel). 2022 May 18;22(10):3827. doi: 10.3390/s22103827.
In this study, a pressurized, water-filled impedance tube (WFIT) was developed to measure the reflection coefficients of sound-absorbing materials under various hydrostatic pressures. The developed WFIT was calibrated using a two-microphone, three-parameter calibration method (3PCM). The accuracy and repeatability of the measured reflection coefficients for the water-air interface in the WFIT were determined by comparing these coefficients with corresponding theoretical reflection coefficients. The WFIT was then used to measure the acoustic reflection coefficient of a porous rubber specimen on three dates, and the corresponding measurement results exhibited satisfactory repeatability. The aforementioned impedance tube was also used to measure the reflection coefficient of a porous rubber specimen under a hydrostatic pressure of 4 P three times on the same day, and one time each on three days, using the same experimental setup and measurement procedure. The results obtained in the aforementioned tests also exhibited satisfactory repeatability. Finally, the WFIT was used to measure the reflection coefficients of porous rubber specimens with various thicknesses under different hydrostatic pressures. The results of this study indicate that the developed WFIT calibrated with the 3PCM can achieve suitable repeatability in the measurement of the reflection coefficients of sound-absorbing materials under various hydrostatic pressures.
在这项研究中，开发了一种加压充水阻抗管（WFIT），用于测量各种静水压力下吸声材料的反射系数。开发的 WFIT 使用双麦克风、三参数校准方法（3PCM）进行校准。通过将 WFIT 中水-空气界面的测量反射系数与相应的理论反射系数进行比较，确定了测量反射系数的准确性和重复性。然后，使用 WFIT 在三天的三个日期测量多孔橡胶样品的声学反射系数，相应的测量结果表现出令人满意的重复性。上述阻抗管还用于在同一天使用相同的实验设置和测量程序，在静水压力为 4 P 下三次测量多孔橡胶样品的反射系数，以及在三天中的每天测量一次。上述测试的结果也表现出令人满意的重复性。最后，使用 WFIT 测量不同静水压力下不同厚度多孔橡胶样品的反射系数。这项研究的结果表明，使用 3PCM 校准的开发的 WFIT 可以在测量各种静水压力下吸声材料的反射系数时达到合适的重复性。
