Investigation of the sound-absorbing behavior of fiber assemblies

In this work the acoustic absorption properties of four common fiber assemblies were studied in the frequency region of 800-6300 Hz using the standing wave tube method. To validate the present experimental setup, firstly the sound absorption property of a rubber foam sample commonly used for noise control was measured, and then compared with the existing data. The absorption coefficients were measured by varying the fiber type, mass, sound frequency, and air gap in the tube in order to examine the contribution of solid fiber against the air in a fibrous assembly. Using an existing theoretical analysis, the relationships between the average diameter of effective pores and the fiber assembly mass for the four fiber types were derived to illustrate certain important connections. Another theoretical model was proposed to analyze the absorption mechanism and predict the absorption coefficient as a function of frequency.