Microperforated panel acoustic structure has been widely used in the field of noise reduction technology. There are many kinds of microperforated panel mufflers designed and manufactured with micro perforated panel acoustic structure. The simplest one is straight pipe muffler, and most of them are impedance composite muffler. The micro perforated plate muffler is made of perforated sheet of enterprise. The common microperforated plate can be made of steel plate (pipe), stainless steel plate (pipe), composite plate (pipe), etc. Because the air layer behind the perforated plate can be filled with porous rock wool, the sound absorption principle of sound absorption material can be used to further reduce the noise reduction in China. In order to obtain wide-band high absorption effect, micro perforated plate structure with observation layer is generally used. The size of the cavity between the microperforated plate and the shell and between the microperforated plate of the muffler varies according to the locking band to be absorbed. Low suction lock chamber is larger than 150 ~ 200 mm, medium frequency is small (80 ~ 120 mm), high frequency is small (30 ~ 50 mm). In general, the depth of the front cavity should be less than that of the back cavity, and the ratio of the depth of the front cavity to the depth of the back cavity should not be greater than 1:3.