Explanation

materials with strong sound energy absorption and noise reduction performance. The sound absorption frequency characteristics of materials are mostly expressed by the sound absorption coefficient measured by the reverberation laboratory at six frequencies of 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz, and there are also the arithmetic mean of the sound absorption coefficient measured by the reverberation laboratory at four octaves of the specified noise reduction coefficient (250-2000HZ), or the sound absorption coefficient at low frequencies (125-500Hz) is not less than 0.2; The intermediate frequency (500-2000Hz) shall not be less than 0.4. Due to different sound absorption mechanisms, it can be divided into two categories: one is porous materials, which rely on many small open channels from the surface to the interior to attenuate sound waves (see porous for sound absorption mechanism), mainly absorbing medium and high frequency sound waves, mainly fiber and materials with open hole structure; The other is flexible materials (absorbing intermediate frequency), membrane materials (low intermediate frequency), plate materials (low frequency) and perforated plates (intermediate frequency) that absorb sound by resonance. The composition use of the above materials can expand the sound absorption range and improve the sound absorption coefficient. Different from acoustic insulation materials, it is often used to reduce the reflection of sound waves in the room, absorb the sound energy of some mixed sound (formed by multiple reflections of sound waves on the indoor wall), reduce the indoor sound level, and improve the impact of reverberation on people; Used to reduce noise in noisy places and improve living environment and working conditions; It is also widely used to reduce the noise of ventilation and air conditioning pipelines.

Classification