Any material can absorb sound, but the degree of absorption varies greatly. Generally, materials with an average sound absorption coefficient greater than 0.2 for the aforementioned six frequencies are classified as sound-absorbing materials. The principle of sound absorption refers to the phenomenon of energy loss when sound waves hit the surface of a material, measured by the sound absorption coefficient α (0 ≤ α ≤ 1). Materials with α > 0.2 are considered sound-absorbing materials.
Porous sound-absorbing materials (such as centrifugal glass wool and rock wool) dissipate sound energy through pore friction and viscous effects, with the sound absorption coefficient increasing as frequency increases. Resonant structures, including Helmholtz resonators, thin plate resonators, and microperforated panels, enhance absorption through resonance at specific frequencies.
Where does the sound go? What is the principle of sound absorption?
January 5, 2026