Sound Absorption Coefficient of Glass Wool

Abstract

This article presents the results of an investigation into the relation between the normal incident sound absorption coefficient and the apparent density of glass wool boards used as a sound absorbent.(1) Only one kind of glass wool boards 64 kg/m3 in apparent density and 2.5 cm in thickness out of 20 kinds made by 3 manufacturers has given a sound absorption characteristic belonging to the mixed type. The sound absorption characteristics of the other kinds of glass wool boards have been shown by experiment to belong to the viscosity-resistance type.(2) The relation between effective apparent density Dea (kg/m3) at which a glass wool board gives 1.00 in sound absorption coefficient and the thickness T (cm) is :Dea=aT -b where a and b are constants fixed by the manufacturer.(3) The relation among apparent density Da (kg/m3), thickness T (cm), distance d (cm) between the center of a sample and the rigid wall, and frequency f o at which the sample gives the maximum sound absorption coefficient is expressed by the following empirical formula : f0= (c/4-aD3a'T)d-' where a and t are constants and c is the speed of sound.

Sound absorption analysis of thermally bonded high-loft nonwovens

“…The highly packed fibrous structure of the relatively heavyweight nonwovens appears to produce a significant reduction in the speed of the sound. A similar result was also found in Aso and Kinoshita’s work 9 in which sound absorption properties of commercially sold glass wool boards were studied. The effect of the sound wave speed on the maximum displacement of the small air volumes at different positions is shown in Figure 17.…”

“…2–14 There is an abundant body of work focused on the influence of thickness, 3–8 bulk density, 5,9 fiber fineness, and shape 2,4–6,10–12 on the acoustical absorptive properties of the nonwovens. The overall conclusions from these studies suggest that fibrous structures with a high sound absorption coefficient require using finer fibers, 2,4–6,10–12 increasing bulk density 5,9 and/or thickness. 3–8…”

Predicting the Air Permeability of Ultrafine Glass Fiber Felts: A Comparison of Artificial Neural Network, Linear Fitting, and Polynomial Fitting

“…Glass fibers are more resistant to high temperatures and corrosion compared to cottons and linens, and they have greater strength and stronger size stability compared to chemical fibers. 1,2 Since their resistance to high temperature and fire is unmatched, glass fiber filtration materials have achieved rapid development.…”