为了保护吸声材料,和增加美观起见,吸声材料上常盖有一层穿孔板.如果穿孔率足够大的话,吸声性质不会受大的影响.就薄板而言,15%的穿孔率已足够了.穿孔板越厚.穿孔率就应越大.此外,一般说来大量的小孔比少量的大孔对吸声效果的影响要来得小(见图64). In order to protect the sound absorbing material and to enhance the appearance, the acoustical absorbing material is often covered with a perforated plate. If the perforating ratio is large enough, the sound absorbing property will not be greatly affected. For the thin plate, the perforation rate of 15% It is sufficient that the thicker the perforated plate is, the larger the perforation rate should be. In addition, in general, a large number of small holes have a smaller influence on sound absorption than a small number of large holes (see Figure 64).