Control of sound transmission in a duct using Helmholtz resonators

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Control of sound transmission in a duct using Helmholtz resonators


Author: Wang, Denghui
Title: Control of sound transmission in a duct using Helmholtz resonators
Degree: M.Eng.
Year: 2016
Subject: Resonators.
Noise control.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: 5, 54 pages : color illustrations
Language: English
InnoPac Record:
Abstract: Helmholtz resonator or HR for short, can be used as a passive noise control method to improve the transmission loss of the duct and pipe inside the ventilation and air conditioning system. A single Helmholtz resonator can produce an obviously sound wave attenuation in a narrow band around its resonance frequency, but the theory and the experimental frequency range has deviation. Various kinds of corrections have been proposed for different size of Helmholtz resonator, therefore it is necessary to determine an accurate correction for the size of the building ventilation pipe. It has also been revealed that a single HR has a narrow attenuation range, thus it is a common method to combine resonators in an array to expand the frequency range of reducing noise. According to the former research, the resonance frequency and transmission loss are governed by the physical dimensions of duct, neck and cavity. By using both Mathematical and transfer matrix method to analyze the acoustic performance of Helmholtz resonator, the project believe that it is necessary to reveal the relationship between the size of resonator and duct with the transmission loss, select a more accurate correction for the duct-HR system, and then provide an operable solution to improve its performance, therefore Helmholtz resonator can be widely used for building noise control.

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