The study on sound-absorbing properties of oblique micro-perforated panel

The oblique micro-perforated panel is distinct to ordinary micro-perforated panel in terms of structure, such as oblique appearance, and open holes are not orthogonal to the panel’s surface. According to Dr. Maa’s theory, the wide-band sound absorption characterization of micro-perforated panel absorber is determined by its high acoustic resistance and low acoustic mass reactance, he also derive its prediction formula in sound absorbing coefficient. The formula whether is applicable to oblique micro-perforated panel is the aim of this research. The study measures the sound absorbing coefficient in reverberation room for 12 sets ordinary micro-perforated panels in 4 different back air space depths, with the purpose of exploring the effects of hole orientation, hole section slope, hole appearance-index, hole area, percentage of perforated area, hole depth, and uneven grade of surface. Key word：micro-perforated panel, oblique micro-perforated panel, Dr. Maa’s theory, sound absorption material 1. Foreword The sound absorption theory of micro-perforated panel had been derived by Dr. Maa at 197