The Acoustic Characterization of Broom Fibers

Natural materials are becoming a valid alternative to traditional synthetic ones for sound absorption applications. In this paper, the acoustic properties of broom fibers are reported and discussed. Broom plants grow up on hills and mountains and are common in many Mediterranean countries. The materials were cut and shredded to prepare several samples. Test specimens made of broom pieces with a diameter from 1.5 mm to 4 mm were prepared. The normal sound absorption for samples with a thickness of 60 mm, 80 mm and 120 mm was then measured. Results are particularly promising especially above 500 Hz, as the samples consistently reported a normal sound absorption above 0.5. The increase in the sample thickness allowed to obtain higher sound absorption at lower frequencies, as generally expected for porous materials. The main limit of the investigated samples was the appearance of sound absorption resonances. These were more evident for the samples composed of pieces with larger diameter, and may be attributed to the loose nature of the tested samples.