摘要
薄纤维层如织物、无纺布等既是室内装饰材料,又具有较好的吸声作用。然而根据传统微孔吸声理论,薄纤维层由于微孔通道太短而只能有很小的吸声作用。但是,在背后有空腔时薄纤维层却表现出良好的吸声效果。说明薄纤维层可能具有某种新的吸声机理。作者首先将穿孔板共振吸声理论应用到薄纤维层当中。由此推导出的共振吸声频率与薄纤维层第一吸声极大值的对应频率基本吻合。然后又将微穿孔共振吸声理论引入。在将材料振动吸声因素考虑进去后,建立了薄纤维层吸声公式。比之传统理论,该公式与实验结果相吻合较好。同时这种理论较好地解释了薄纤维层在作为护面材料或紧贴墙壁时吸声系数等于或接近于零,而作为窗帘或背后有空腔时却具有较好的吸声效果的这一声学现象。
Thin fiber layers such as fabrics and nonwovens have been used as the decorate materials in the room extensively.While it is also efficient at absorb sound and noise.Now,there are not special theory for thin fiber layers to explain the phenomenon that thin fiber layers absorb sound less when it is the cover fabric of sound absorber or rigid back,but has good sound absorption ability when it is hang as the curtains or have back cave behind it.That means there are probably another sound absorption mechanisms different from classical theory for thin fiber layers.Firstly,perforated resonance absorption theory is applied.It is found that the calculated resonance frequency is agreement with the first maximum sound absorption frequency obtained from the test.To get the exact result of sound absorption coefficient agree with the practice,the micro perforated sound absorption theory is applied also.Owning to this theory is not well agree with the testing result,a new idea is put forward that the vibration of materials must be considered as the absorption factor.The new theory which consider both the pore absorption and vibration absorption are more agreement with the testing results than classical theory.In addition and for most important,the new theory can explain the phenomenon that thin fiber layer absorb sound less when it is the cover fabric of sound absorber or rigid back,but more efficient when it is hung as the curtains or have back cave behind it.
基金
陕西省重点实验室项目(05JS07)
关键词
建筑声学
声阻抗率
共振吸声理论
膜振动
薄纤维层
building acoustics
specific acoustic impedance
perforated resonance absorption theory
membrane vibration theory
thin fiber layer
