scholarly journals A Multi-Tone Sound Absorber Based on an Array of Shunted Loudspeakers

2018 ◽  
Vol 8 (12) ◽  
pp. 2484 ◽  
Author(s):  
Chaonan Cong ◽  
Jiancheng Tao ◽  
Xiaojun Qiu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Sound Absorption ◽  
Interaction Analysis ◽  
Low Frequency ◽  
Normal Incidence ◽  
Acoustic Properties ◽  
The Finite Element Method ◽  
Sound Absorber ◽  
Modal Solution

It has been demonstrated that a single shunted loudspeaker can be used as an effective low frequency sound absorber in a duct, but many shunted loudspeakers have to be used in practice for noise reduction or reverberation control in rooms, thus it is necessary to understand the performance of an array of shunted loudspeakers. In this paper, a model for the parallel shunted loudspeaker array for multi-tone sound absorption is proposed based on a modal solution, and then the acoustic properties of a shunted loudspeaker array under normal incidence are investigated using both the modal solution and the finite element method. It was found that each shunted loudspeaker can work almost independently where each unit resonates. Based on the interaction analysis, multi-tone absorbers in low frequency can be achieved by designing multiple shunted loudspeakers with different shunt circuits respectively. The simulation and experimental results show that the normal incidence sound absorption coefficient of the designed absorber has four absorption peaks with values of 0.42, 0.58, 0.80, and 0.84 around 100 Hz, 200 Hz, 300 Hz, and 400 Hz respectively.

scholarly journals Low Frequency Sound Absorption by Optimal Combination Structure of Porous Metal and Microperforated Panel

2019 ◽  
Vol 9 (7) ◽  
pp. 1507 ◽  
Author(s):  
Xinmin Shen ◽  
Panfeng Bai ◽  
Xiaocui Yang ◽  
Xiaonan Zhang ◽  
Sandy To
Keyword(s):  
Finite Element ◽  
Sound Absorption ◽  
Search Algorithm ◽  
Low Frequency ◽  
Porous Metal ◽  
Cuckoo Search ◽  
Element Model ◽  
Frequency Sound ◽  
Sound Absorber ◽  
Standing Wave Tube

The combination structure of a porous metal and microperforated panel was optimized to develop a low frequency sound absorber. Theoretical models were constructed by the transfer matrix method based on the Johnson—Champoux—Allard model and Maa’s theory. Parameter optimizations of the sound absorbers were conducted by Cuckoo search algorithm. The sound absorption coefficients of the combination structures were verified by finite element simulation and validated by standing wave tube measurement. The experimental data was consistent with the theoretical and simulation data, which proved the efficiency, reliability, and accuracy of the constructed theoretical sound absorption model and finite element model. The actual average sound absorption coefficient of the microperforated panel + cavity + porous metal + cavity sound absorber in the 100–1800 Hz range reached 62.9615% and 73.5923%, respectively, when the limited total thickness was 30 mm and 50 mm. The excellent low frequency sound absorbers obtained can be used in the fields of acoustic environmental protection and industrial noise reduction.

scholarly journals Design of an Acoustic Bender Transducer for Active Sonobuoys

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1691 ◽  
Author(s):  
Pyo ◽  
Shim ◽  
Roh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Performance ◽  
Structural Parameters ◽  
Underwater Vehicles ◽  
Acoustic Properties ◽  
Voltage Response ◽  
Sound Waves ◽  
The Finite Element Method ◽  
High Detection

Recent underwater vehicles can operate with a much lower level of noise, which increases the need for an active sonobuoy with a high detection performance. These active sonobuoys mainly use bender transducers as a projector that emits sound waves. In this study, we designed a high-performance bender transducer and verified the validity of the design through experiments. For this purpose, first we analyzed the variation of the peak transmitting voltage response (TVR) level and peak TVR frequency of the bender transducer, in relation to its structural parameters. The performance of the bender transducer was analyzed using the finite element method. Then we derived the optimal structure of the bender transducer to achieve the highest TVR. Based on the design, a prototype of the bender transducer was fabricated and its acoustic properties were measured to confirm the validity of the design.

scholarly journals Study on Low-Frequency Band Gap Characteristics of a New Helmholtz Type Phononic Crystal

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1379
Author(s):  
Dong-Hai Han ◽  
Jing-Bo Zhao ◽  
Guang-Jun Zhang ◽  
Hong Yao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Band Gap ◽  
Lattice Constant ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Equivalent Model ◽  
Frequency Noise ◽  
The Finite Element Method ◽  
Symmetric Structure

In order to solve the problem of low-frequency noise of aircraft cabins, this paper presents a new Helmholtz type phononic crystal with a two-dimensional symmetric structure. Under the condition of the lattice constant of 62 mm, the lower limit of the first band gap is about 12 Hz, and the width is more than 10 Hz, thus the symmetric structure has distinct sound insulation ability in the low-frequency range. Firstly, the cause of the low-frequency band gap is analyzed by using the sound pressure field, and the range of band gaps is calculated by using the finite element method and the spring-oscillator model. Although the research shows that the finite element calculation results are basically consistent with the theoretical calculation, there are still some errors, and the reasons for the errors are analyzed. Secondly, the finite element method and equivalent model method are used to explore the influence of parameters of the symmetric structure on the first band gap. The result shows that the upper limit of the first band gap decreases with the increase of the lattice constant and the wedge height and increases with the increase of the length of wedge base; the lower limit of the band gap decreases with the increase of the wedge height and length of wedge base and is independent of the change of lattice constant, which further reveals the essence of the band gap formation and verifies the accuracy of the equivalent model. This study provides some theoretical support for low-frequency noise control and broadens the design idea of symmetric phononic crystal.

Estimation of Sound Absorption Performance of Complex Perforated Panel Absorbers by Numerical Finite Element Method and Examinining the Role of Different Layouts Behind It

2019 ◽  
Vol 18 (03) ◽  
pp. 1950013
Author(s):  
Z. Hashemi ◽  
M. R. Monazzam ◽  
A. Fahim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Sound Absorption ◽  
Current Method ◽  
The Finite Element Method ◽  
Impedance Tube ◽  
Absorption Performance ◽  
Numerical Finite Element ◽  
Element Method

Perforated panels are one of the structures that are widely used nowadays. The sound absorption behavior of materials is studied by solving the equations governing the wave propagation in these materials. In this paper, the finite element method (FEM) was used to predict the absorption performances of few different perforated composite panels. Also, the studied structures were examined by two-microphone impedance tube to validate the results of the numerical method. The relative consistency of the results of the current method with the results of the impedance tube suggests the accuracy of this method in simulating the absorption rate of perforated composites. In addition, the results of evaluating various layouts (arrangements) showed that the use of absorber materials with higher flow resistivity at the back of the perforated panel and at the beginning of the sound wave entry increases the absorption performance by 1.6 times than that of the inverse layout ratio.

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