An experimental and theoretical study on environment-friendly sound absorber sourced from nettle fibers. (September 2020)

• Record Type: Journal Article
• Authors: Raj, Manish; Fatima, Shahab; Tandon, Naresh
• Is Part Of: Journal of building engineering. Volume 31(2020)
• Publication Date: 2020-09
• Subjects: Noise reduction coefficient -- Green sound absorbers -- Allard model -- Genetic algorithm; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2020.101395
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: This is a comprehensive study on a sustainable sound absorber sourced from nettle fibers. The fibers were thoroughly characterized for properties linked to its performance as an effective and efficient sound absorber, like density, surface roughness, surface morphology, physical strength, and thermal stability. Nettle fibers were converted into non-woven form and characterized for its acoustical characteristics. The obtained results of sound absorption coefficients were analyzed to determine the optimum thickness for optimum performance during practical noise control applications. Further, a comprehensive comparison of experimental results and theoretical results obtained from empirical models were compared. The genetic algorithm and Allard model was used to estimate the characteristics impedance and complex wavenumber. These characteristics were further used to visualize the effect of the air gap behind the sound absorber. The results obtained showed nettle fiber to be an effective sound absorber. The results of theoretical and experimental studies matched well. The average noise reduction coefficient up to 0.72 was achieved, which was further boosted to 0.80 on incorporating a 30 mm air gap. The performance of nettle fiber with optimum thickness was compared with commercial glasswool, and waste jute fibers. The comparison established nettle to have better sound absorption properties. Highlights: Characterization of nettle fibers is performed for all properties affecting their performance as a good sound absorber. A low cost alternative of commercial glasswool is suggested. The fibers are studied for sound absorption in non-woven form for better repeatability of results. NRC of nettle fibers is reported to be higher than commercial glasswool.. An alternate way of analyzing the effect of air-gap is proposed by application of optimization techniques.