Centrifugal glass wool has better sound absorption performance at high frequency in sound.The main factors affecting the sound absorption performance of centrifugal glass wool are thickness, density and air flow resistance.Density is the weight of material per cubic meter.Air resistance is the ratio of air pressure to air velocity on both sides of a material per unit thickness.Air flow resistance is the most important factor affecting the sound absorption performance of centrifugal glass wool.The flow resistance is too small, indicating that the material is sparse, air vibration is easy to pass through, and the sound absorption performance decreases.The flow resistance is too large, indicating that the material is dense, air vibration is difficult to pass in, and the sound absorption performance also decreases.For centrifugal glass wool, the sound absorption performance has the best flow resistance.
In practical engineering, it is difficult to measure air flow resistance, but it can be roughly estimated and controlled by thickness and bulk density.
1. With the increase of thickness, the sound absorption coefficient of medium and low frequency increases significantly, but the high frequency does not change much (the high frequency absorption is always large).
2. With the thickness unchanged and the bulk density increased, the sound absorption coefficient of medium and low frequency also increased;However, when the bulk density increases to a certain degree, the material becomes compacted, the flow resistance is greater than the optimal flow resistance, and the sound absorption coefficient decreases instead.For centrifugal glass wool with a bulk density of 16Kg/m3 with a thickness of more than 5cm, the low-frequency 125Hz is about 0.2, and the sound absorption coefficient of medium-high frequency (>500Hz) is close to 1.When the thickness continues to increase from 5cm, the low-frequency sound absorption coefficient gradually increases, and when the thickness is more than 1m, the low-frequency sound absorption coefficient of 125Hz is also close to 1.When the thickness remains unchanged and the bulk density increases, the low-frequency sound absorption coefficient of the centrifugal glass wool will also continuously improve. When the bulk density is close to 110kg/m3, the sound absorption performance reaches the maximum value, and the thickness of 50mm and the frequency of 125Hz are close to 0.6-0.7.When the bulk density exceeds 120kg/m3, the sound absorption performance decreases instead, because the material becomes densified and the sound absorption performance of medium and high frequencies is greatly affected. When the bulk density exceeds 300kg/m3, the sound absorption performance decreases greatly.The thickness of sound-absorbing glass wool commonly used in architectural acoustics is 2.5cm, 5cm, 10cm, and its bulk density is 16, 24, 32, 48, 80, 96, and 112kg/m3.Centrifugal glass wool with a thickness of 5cm and a thickness of 12-48kg/m3 is usually used.