Noise barriers with non-uniform edge impedance

Pao Yue-kong Library Electronic Theses Database

Noise barriers with non-uniform edge impedance

 

Author: Li, Sijie
Title: Noise barriers with non-uniform edge impedance
Degree: M.Eng.
Year: 2015
Subject: Noise barriers -- Design and construction.
Noise control.
Transportation noise.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: 70 pages : color illustrations
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2826147
URI: http://theses.lib.polyu.edu.hk/handle/200/8236
Abstract: In recent decades, with the development of transportation and expressway, the noise generated from the traffic becomes more and more seriously. To control and reduce the noise are the popular topics in recent acoustics study. The noise reduction of noise barrier is mainly used insertion loss to evaluate and this dissertation uses the model experiment method to test the insertion loss. The model experiment method will return to the original condition in the outside environment. Noise barriers have different kinds of structures, this article is mainly concerned with the performance and comparison of some different kinds of edges. All edges are in the same condition with same materials, same height and same experiment environment. And next, we used the MATLAB and EXCEL to calculate and analysis how the structure of the edges influences the performance. Finally, to point out which kind of edge will perform better than others in which range of frequency. The results show that the uniform edges which manufactured by MPP method with perforation ratio of 0.43% performs well in the range of 1900-2000hz and 2300-2700hz with the ΔIL of 2dB more than normal barrier. And the non-uniform edge and the non-uniform edge with different impedance, which these two have the perforation ratio of 0.44%, perform well in the range of 150-250hz with the ΔIL of 1.5dB more than normal barrier. And all edges perform similar to other with a distance of 90cm to the central of the barrier.

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