Normal incidence absorption coefficient spectra of samples made from glued wood chips have been measured for various mesh sizes, bulk densities, thicknesses, and air gaps. Increasing thickness introduces additional layer resonance peaks and shifts the initial peak towards lower frequencies. The wood chip samples composed of the smallest mesh sizes were found to offer the highest sound absorption, comparable with that of the same thickness of materials made from synthetic fibers. Measured absorption spectra are compared with predictions of four models for the acoustical properties of rigid porous media. These include a model for slanted parallel identical uniform slits (SS), the Johnson-Champoux-Allard (JCA) and Johnson-Champoux-Allard-Lafarge (JCAL) models for arbitrary pore structures, and model for a non-uniform pore size distribution (NUPSD). Porosity and flow resistivity values have been determined non-acoustically. However, the tortuosity and characteristic lengths required for the JCA model have been obtained by fitting the measured absorption spectra. The thermal permeability required for the JCAL model has been deduced indirectly from the fitted tortuosity through a relationship with standard deviation of the pore size distribution due to the NUPSD model. JCAL and JCA models give the best agreement overall, but predictions of the SS and NUPSD models that use only the fitted tortuosity in addition to measured porosity and flow resistivity are found to give comparable agreement with data for many samples. SS and NUPSD predictions are improved by increasing the tortuosity values compared with those obtained by fitting the JCA model. The study should encourage the creation of sustainable sound-absorbing materials from wood chip wastes.

中文翻译：

---

木片吸音器：测量和模型

测量了由胶合木片制成的样品的不同网格尺寸、堆积密度、厚度和气隙的垂直入射吸收系数光谱。增加厚度会引入额外的层共振峰值，并将初始峰值移向较低频率。研究发现，由最小网格尺寸组成的木片样品具有最高的吸音性，与相同厚度的合成纤维材料的吸音性相当。将测量的吸收光谱与刚性多孔介质声学特性的四个模型的预测进行比较。其中包括倾斜平行相同均匀狭缝 (SS) 模型、任意孔隙结构的 Johnson-Champoux-Allard (JCA) 和 Johnson-Champoux-Allard-Lafarge (JCAL) 模型以及非均匀孔径分布模型（国家公共服务发展署）。孔隙率和流阻值已通过非声学方法测定。然而，JCA模型所需的弯曲度和特征长度是通过拟合测量的吸收光谱获得的。 JCAL 模型所需的热导率是通过与 NUPSD 模型的孔径分布标准差的关系从拟合的曲折度间接推导出来的。 JCAL 和 JCA 模型总体上给出了最好的一致性，但仅使用拟合的曲折度以及测量的孔隙率和流阻率的 SS 和 NUPSD 模型的预测结果与许多样品的数据给出了相当的一致性。与通过拟合 JCA 模型获得的结果相比，通过增加弯曲度值可以改进 SS 和 NUPSD 预测。该研究应鼓励利用木片废料制造可持续的吸音材料。