The hole gypsum board has a cylindrical hole penetrating through the front and the back of the gypsum board, and a backing material having a gas permeability and a sound absorbing material capable of absorbing incident sound energy are attached to the back surface of the gypsum board. The sound absorption mechanism is that there are a large number of tiny connected pores inside the material, and the sound waves along the pores can penetrate into the interior of the material, and friction with the material converts the acoustic energy into heat energy.
The sound absorption characteristic of the porous sound absorbing material is that the sound absorption coefficient gradually increases as the frequency increases, which means that the low frequency absorption has no high frequency absorption.
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