Current sound-absorbing materials are mostly loose and porous, such as slag wool and blankets. Their sound absorption mechanism involves sound waves penetrating into the material's pores, which are typically interconnected open pores. These pores cause friction and viscous resistance from air molecules and mechanical vibrations of fine fibers, thereby converting sound energy into thermal energy. The sound absorption coefficient of these porous materials generally increases from low frequencies to high frequencies, making them more effective at absorbing high-frequency and mid-frequency sounds.
