Assessing the effect of air- gap in acoustic panels’ sound absorption made ofdate palm fiber (Phoenix dactylifera)

By considering the high consumption of acoustic panels in the related industries and the importance of natural fibers’ consumption as proper sound absorber replacement for synthetic fibers, the probability of producing acoustic panels made of date-palm-trunk fibers and sodium silicate adhesive is assessed. The effect of thickness, density, particle length, adhesive percentage and air-gap on sound absorption coefficient are measured according to ASTM 10534-2 ISO at 250, 500, 1000, 2000 and 4000 Hz frequencies. The results reveal that an increase in thickness shifts the sound absorption coefficient peak towards lower frequencies. An increase in density increases the sound absorption coefficient and at high frequencies it decreases. An increase in particle length increases sound absorption coefficient and at 4000 Hz this process is reversed. An increase in adhesive percentage decrease sound absorption coefficient at high frequencies. The effect of 25 and 41 mm air-gap on sound absorption frequency on the best produced panels of 32 and 16 mm thick, respectively, is assessed.  Panels of low thickness at higher air-gap enhance sound absorption coefficient at all frequencies. This fact can be highly contributive in reducing production cost of environment-friendly acoustic panels where, silicate sodium adhesive is consumed.