This paper investigates the mechanisms that can be used to enhance the absorption performance of poro-elastic materials in the viscous regime. It is shown that by adding small inclusions in a poro-elastic foam layer, a mass–spring effect can be introduced. If the poro-elastic material has relatively high viscous losses in the frequency range of interest, the mass–spring effect can enhance the sound absorption of the foam by introducing an additional mode in the frame and increasing its out-of-phase movement with respect to the fluid part. Moreover, different effects such as the trapped mode effect, the modified-mode effect, and the mass–spring effect are differentiated by decomposing the absorption coefficient in terms of the three energy dissipation mechanisms (viscous, thermal, and structural losses) in poro-elastic materials. The physical and geometrical parameters that can amplify or decrease the mass–spring effect are discussed. Additionally, the influence of the incidence angle on the mass–spring effect is evaluated and a discussion on tuning the inclusion to different target frequencies is given.

本文研究了可用于提高多孔弹性材料在粘性状态下的吸收性能的机制。结果表明，通过在多孔弹性泡沫层中添加小夹杂物，可以引入质量弹簧效应。如果多孔弹性材料在感兴趣的频率范围内具有相对较高的粘性损失，则质量弹簧效应可以通过在框架中引入附加模式并增加其异相运动来增强泡沫的吸声到流体部分。此外，通过根据孔隙中的三种能量耗散机制（粘性损耗、热损耗和结构损耗）分解吸收系数，可以区分不同的效应，例如俘获模式效应、修正模式效应和质量-弹簧效应。弹性材料。讨论了可以放大或减少质量-弹簧效应的物理和几何参数。此外，还评估了入射角对质量-弹簧效应的影响，并讨论了将夹杂物调整到不同的目标频率。