The purpose of this paper is to calculate an accurate sound absorption coefficient for a micro-perforated panel absorber (MPPA). When the sound absorption coefficient is calculated, there is a difference between the measurement and the calculation. In the calculation, a resistive end correction coefficient (β) of 2 or 4 and a reactive end correction coefficient (δ) of 0.85 are generally applied. However, using an impedance tube test, we confirm that end correction coefficients change depending on the specification of the micro-perforated panel. The resistive end correction coefficient is in the range of 2–4 and increases when the hole diameter and the porosity decrease and the panel thickness increases. The reactive end correction coefficient is less than 0.85 and increases when the hole diameter and the panel thickness increase and the porosity decreases. Based on our experimental results, we derive new coefficient formulas expressed by the hole diameter (d), the hole spacing (b), the porosity (p) and the panel thickness (t). To verify the proposed formulas, the sound absorption coefficient calculation is compared with the measurement, which confirms that the absorption coefficient is affected by the ratio between the air mass inside the hole and the added air mass outside the hole. The relation between the two masses can be confirmed by the ratio of the panel thickness (t) to the hole diameter (d). In a single-layer MPPA, when t/d is greater than or equal to about 2, the absorption peak level of calculations, no matter what β is applied, is similar to the measurement. On the other hand, when t/d is less than about 2, the calculation is greatly affected by β. The sound absorption coefficients for both single- and double-layer MPPAs are compared according to the proposed formulas and coefficients of other researchers. The calculation of the proposed formulas among calculations is in good agreement with the measurement.

中文翻译：

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取决于微孔板的几何特性的端部校正系数

本文的目的是为微孔板式吸声器（MPPA）计算准确的吸声系数。计算吸声系数时，测量值与计算值之间会有差异。在计算中，电阻端校正系数（β）为2或4，而电抗端校正系数（δ）通常应用0.85的）。但是，通过阻抗管测试，我们确认端部校正系数会根据微孔板的规格而变化。电阻端校正系数在2-4的范围内，并且当孔径和孔隙率减小且面板厚度增加时增大。反应端校正系数小于0.85，并且当孔径和面板厚度增加且孔隙率降低时增加。根据我们的实验结果，我们得出了由孔直径（d），孔间距（b），孔隙率（p）和面板厚度（t）表示的新系数公式。）。为了验证所提出的公式，将吸声系数计算与测量值进行了比较，这确定了吸声系数受孔内空气质量与孔外空气质量之比的影响。可以通过面板厚度（t）与孔径（d）之比来确认两个质量之间的关系。在单层MPPA中，当t / d大于或等于2时，无论应用什么β，计算的吸收峰水平都类似于测量。另一方面，当t / d小于约2时，计算会受到β的极大影响。根据建议的公式和其他研究人员的系数比较了单层和双层MPPA的吸声系数。计算中建议的公式的计算与测量结果非常吻合。