Metallic hollow spheres and polyurethane resin are excellent sound insulation and sound absorption materials. In this study, the surface modified 316L stainless steel hollow spheres were added into polyurethane by casting method. The influence of the volume fraction and diameter of the hollow spheres on the sound insulation and sound absorption performance of the Metallic-Hollow-Sphere/Polyurethane (MHSP) acoustic composites was investigated by impedance tube method and the relevant acoustic mechanism was discussed. When the volume fraction of hollow spheres is 45% and the diameter is 2.5 mm, composite has the best sound insulation performance. And when the volume fraction of hollow spheres is 60% and the diameter is 2.5 mm, composite has the best sound absorption performance. Due to the mass effect, damping effect, change of acoustic impedance and multiple interface of composites, sound waves will reflect, refract and scatter many times in the process of propagation, thus losing lots of sound energy to improve the sound insulation performance. The sound absorption mechanism of MHSP is that the friction, viscosity and reflection of sound waves in the pores of polyurethane, cavities of the hollow spheres and interfaces will cause the loss of sound energy and turn it into heat energy.

金属空心球和聚氨酯树脂是出色的隔音和吸声材料。在这项研究中，将表面改性的316L不锈钢空心球通过浇铸方法添加到聚氨酯中。通过阻抗管法研究了空心球的体积分数和直径对金属-空心球/聚氨酯（MHSP）声复合材料的隔音和吸声性能的影响，并探讨了相关的声机理。当空心球的体积分数为45％，直径为2.5 mm时，复合材料具有最佳的隔音性能。当空心球的体积分数为60％，直径为2.5 mm时，复合材料具有最佳的吸声性能。由于质量效应，阻尼效应，复合材料的声阻抗和多界面变化，声波在传播过程中会多次反射，折射和散射，从而损失大量声能，从而提高了隔声性能。MHSP的吸声机理是，声波在聚氨酯孔隙，中空球体和界面的空腔中的摩擦，粘度和反射会引起声能的损失并将其转化为热能。