Sound absorption principle of aluminum fiber sound-absorbing board

1、 Sound absorption principle of porous materials

Principle: The vibration of the sound source causes waves, and the propagation of waves is due to the interaction between particles in the medium. In a continuous medium, the vibration of any point will directly cause the vibration of adjacent particles. The propagation of sound waves in the air satisfies its principles.

Porous sound-absorbing materials have many small gaps and continuous bubbles, thus possessing excellent breathability. When sound waves incident on the surface of porous materials, there are two main mechanisms that cause the attenuation of sound waves: firstly, the vibration generated by sound waves causes the movement of air in small holes or gaps, causing friction with the hole wall. The air immediately adjacent to the hole wall and the fiber surface is not easily moved by the hole wall. Due to the effects of friction and viscous force, a considerable portion of sound energy is converted into heat energy, resulting in the attenuation of sound waves and the reduction of reflected sound to achieve the purpose of sound absorption; Secondly, the heat loss caused by the air in the small hole and the heat exchange between the hole wall and the fiber also leads to the attenuation of sound energy. In addition, high-frequency sound waves can accelerate the vibration speed of air particles between voids, and also accelerate the heat exchange between air and hole walls. This enables porous materials to have good high-frequency sound absorption performance.

2、 Classification of porous sound-absorbing materials: Porous sound-absorbing materials can be divided into compliant and non compliant materials based on their flexibility in material selection. Compliant sound-absorbing materials mainly achieve sound absorption through internal friction, air friction, and heat exchange within the framework; Non compliant materials mainly rely on the viscosity of air to achieve sound absorption function. Porous sound absorbing materials can be divided into four categories: organic fiber materials, inorganic fiber materials, sound absorbing metal materials and foam materials according to their physical characteristics and appearance.