The perforated gypsum board is composed of cylindrical holes through the front and back of the gypsum board. The back of the gypsum board is pasted with the back cover material with air permeability and the sound absorption material that can absorb the radiation energy.

The sound absorption mechanism is that there are a lot of tiny connected pores in the material. Along these pores, the sound wave can go deep into the material and produce friction with the material to convert the sound energy into heat energy.

The absorption coefficient of porous materials increases with the increase of frequency, which means that the low-frequency absorption is not as good as the high-frequency absorption.

The sound absorption mechanism of this structure is resonance absorption of thin plate.

At the resonance frequency, a large amount of sound energy is absorbed due to the violent vibration of the thin plate. The resonance absorption of thin plate is mostly good at low frequency.

To sum up: one is to absorb high frequency, the other is to absorb low frequency.