The Acoustic Characterization of Broom Fibers Umberto Berardi a , Gino Iannace b , and Maria Di Gabriele c a Department of Architectural Science, Ryerson University, Toronto, ON, Canada; b Department of Architecture and Industrial Design, Second University of Naples, Aversa, Italy; c Department of Engineering, University of Sannio, 5 Benevento, Italy ABSTRACT Natural materials are becoming a valid alternative to traditional synthetic ones for sound absorption applications. In this paper, the acoustic proper- ties of broom fibers are reported and discussed. Broom plants grow up on 10 hills and mountains and are common in many Mediterranean countries. The materials were cut and shredded to prepare several samples. Test speci- mens 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 15 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 gen- erally expected for porous materials. The main limit of the investigated samples was the appearance of sound absorption resonances. These were 20 more evident for the samples composed of pieces with larger diameter, and may be attributed to the loose nature of the tested samples. 摘要 天然材料日益成为吸声应用中传统合成材料的有效替代品。本文报告和讨 论了笤帚纤维的声学性能。笤帚植物生长在山区，在许多地中海国家都很 常见。在本研究中，将材料切割并切碎，以制备由直径为 1.5 mm 至 4 mm 25 的扫帚片制成的试样；然后，测量厚度为 60 mm、80 mm 和 120 mm 的样 品的正常吸声性能。结果令人振奋，特别是在500Hz以上的条件下，样品 一致地展示了超过 0.5 的正常吸声性能。增加样品厚度可在较低频率下获 得较高的吸声性能，这与我们通常对多孔材料的预期一致。所研究样品的 主要限制是存在吸声共振，在由较大直径的块组成的样品上表现更为明 30 显，这可能与所测试样品的松散性质有关。 KEYWORDS Acoustics; green materials; natural material; sound absorption Introduction The increasing attention towards energy saving issues and the need of reducing the adverse environmental impact of human activities is leading to a more responsible use of locally available resources. In this context, the use of natural materials in the building sector is often suggested as an important strategy towards sustainability. This entails the need to investigate the properties of 35 natural materials that, due to their characteristics (good thermal insulation, not harmful to human health, biodegradable, recyclable, widely available and cheap), can be used as an alternative to synthetic fibers. Scientific literature includes several studies about the use of natural fibers as reinforcing agents of composite materials (Ekici et al. 2012, Chidichimo et al. 2015; Peng et al. 2015). At the same time, CONTACT Umberto Berardi Department of Architectural Science, Ryerson University, 350 Victoria Street, Toronto, M5B 2K3, ON, Canada. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/WJNF. © 2017 Taylor & Francis Group, LLC JOURNAL OF NATURAL FIBERS 2017, VOL. 00, NO. 00, 1–6 http://dx.doi.org/10.1080/15440478.2017.1279995