Abstract:

In this research work the amount of sound absorption in different multi-layer structures made from nonwoven layers and placed in various configurations were measured and analysed. After producing nonwovens with specified geometric characteristics, multi-layer structures with different configurations were made. We investigated the multi-layer structures and found out that when the number of layers in a structure increases, its sound absorption would rise. It was also observed that the increase in sound absorption at lower frequencies only occurs when the thickness of nonwovens is increased. However, at high frequencies the thickness of the nonwoven layers has a slight influence on the sound absorption of the multi-layer structure. It was also seen in the multi-layer structures that, with a less distance between layers, increasing the number of layers in the structures would positively improve the sound absorption. Hence, this property can be improved either by increasing the distance between the layers or simultaneously decreasing the number of layers in the multi-layer structures, although this trend would be true for panels having less than four nonwoven layers and at frequencies up to 1000 Hz.