Micro-perforated panel, as sound absorbing material, has been used for 30 years. However, the use of micro-perforated panel was sometimes not very effective since its absorptive bandwidth is not wide enough yet. The hole diameter of 0.5mm is the smallest hole so far, which is obtained by using usual mechanical method to process a panel of thickness 0.5mm or thicker. Now a new technology to produce minor diameter hole has been developed in a metal panel of thickness 0.5mm. The cost to get minor diameter hole using the technology is much lower than laser processing method or electric spark method. A great amount of micro-perforated metal panel with hole diameter of 0.3mm has been produced successfully. The measured results in reverberation chamber show that sound absorption coefficient of single layer micro-perforated panel is more than 0.5 in 3～4 octave bands. Micro-perforated panel silencer tests have been made.
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