Comparison of Experimental and Empirical Approaches for Determination of Sound Absorption Properties of Bagasse and Cornhusk Fibers

ABSTRACT

The significant physical, economic and environmental properties of some agricultural wastes have made them viable alternatives for the conventional sound-absorbing materials. Therefore, it is necessary to identify these types of agricultural wastes and investigate the acoustic behavior and applicability of mathematical predictive models for sound absorption of the samples fabricated from such wastes. In this regard, this study was conducted to investigate the sound absorption coefficient (SAC) values of the samples made from sugarcane and corn husk wastes using experimental and empirical methods. The morphological examination of sugarcane and corn husk fibers was performed by Field emission scanning electron microscopy (FESEM). Having prepared the fibers, several cylindrical samples with a constant density (150 kg/m3) and different thicknesses (20, 30 and 40 mm) were fabricated. The SAC values, porosity and airflow resistivity of these samples were then measured using ISO 10534–2 (impedance tube system), SEM and ASTM C522–03, respectively. The Delany-Bazley (DB) analytical model and the reversed Delany-Bazley model with Nelder-Mead Simplex (DB-NMS) were also used to predict the SAC values. Based on the acoustic performance of the fabricated samples, the SAC values for the thickness of 40 mm and frequency of 500 Hz were, respectively, 0.42 and 0.54 for sugarcane and corn. Increasing the thickness of the samples and creating an air gap behind them were found to be the acceptable approaches for improving the sound absorption. It was found that the DB-NMS model would appropriately follow the experimental results. The purposeful application of agricultural waste and analytical acoustic models because of their outstanding benefits and an effective approach will encourage the usability of natural materials (as eco-friendly, cheap and efficient acoustic products) in indoor and outdoor commercial applications.

摘要

一些农业废物的重要物理、经济和环境特性使其成为传统吸声材料的可行替代品. 因此, 有必要识别这些类型的农业废物, 并研究这些废物制成的样品吸声的声学行为和数学预测模型的适用性. 在这方面, 本研究采用实验和经验方法研究了甘蔗和玉米壳废弃物样品的吸声系数 (SAC) 值. 用场发射扫描电镜 (FESEM) 对甘蔗和玉米壳纤维进行了形态观察. 制备纤维后, 制备了几个密度恒定 (150kg/m3) 和不同厚度 (20、30和40mm) 的圆柱形样品. 然后分别使用ISO 10534-2 (阻抗管系统)、SEM和ASTM C522–03测量这些样品的SAC值、孔隙度和气流电阻率. 还使用Delany-Bazley (DB) 分析模型和Nelder-Mead单纯形反向Delany-Bazley模型 (DB-NMS) 预测SAC值. 基于所制备样品的声学性能, 对于甘蔗和玉米, 厚度为40mm和频率为500Hz的SAC值分别为0.42和0.54. 增加样品的厚度并在样品后面形成气隙是提高吸声性能的可接受方法. 发现DB-NMS模型与实验结果吻合较好. 有目的地应用农业废物和分析声学模型, 因为它们具有显著的效益和有效的方法, 将鼓励在室内和室外商业应用中使用天然材料 (作为环保、廉价和高效的声学产品).

KEYWORDS:

• Agricultural waste
• sound absorption
• impedance tube
• empirical model
• bagasse
• cornhusk

关键词:

• 农业废弃物
• 吸声
• 阻抗管
• 经验模型
• 甘蔗渣
• 玉米壳

Acknowledgments

We are thankful to Tarbiat Modares University for providing the necessary laboratory facilities for this work.

Disclosure statement

The author(s) declare that there is no conflict of interests regarding the publication of this paper