Sound Absorbing Properties of Molded Fiberglass Panels for Use in Vehicle Noise Control

Molded fiberglass headliners and headliners are widely used in vehicles for controlling sound. These parts frequently must be molded to fit structural contours thus resulting in variations in part thickness, bulk density and spacing of the part from underlying sheet metal surfaces. This paper reviews the results of a study which was conducted to determine the effects of these variables on the sound absorption characteristics of the material. Random incidence sound absorption coefficients over the frequency range of 80 to 6300 Hz. were measured using fiberglass panels in thicknesses ranging from 1/4 to 2 inches and bulk densities from 1 to 8 pounds per cubic foot with air spaces from 0 to 1 inch.