Comparing sound absorption characteristic of acoustic boards made of　Aspen particles and different percentage of Wheat and Barely straws

摘要

In this investigation, the influences of two kinds of agricultural residues (Wheat and Barely straws) mixed with aspen particle were studied for use as insulation boards. The manufacturing parameters were: a kind of straw(Wheat and Barely straw), different percentage of straws( 0/100, 10/90, 20/80 and 30/70 weight of straw/ aspen particles) of 0,10,20, and 30 wt% and specific gravity of 0.2,0.4 and 0.6 gr/cm3. A commercial ureaformaldehyde adhesive as used as binder. Sound absorption coefficients were measured at five frequencies (250, 500, 1000, 2000 and 4000 hertz).The results showed when frequencies increased, sound absorption increased until it reached to frequency of 2000 Hz but at 4000 Hz sound absorption coefficient decreased. Between manufacturing parameters, kind of straw didn’t have significant influences on sound absorption coefficients. The best density for absorb sound waves under 1000 Hz was 0.4 gr/cm3 with 30% of straws. For waves with frequency higher than 1000 Hz the best density was 0.2gr/cm 3 with 30% of straws.