Hybrid phononic crystals for broad-band frequency noise control by sound blocking and localization

2012 ◽  
Vol 132 (5) ◽  
pp. EL411-EL416 ◽  
Author(s):  
Sungmin Yoo ◽  
Yoon Jae Kim ◽  
Yoon Young Kim
Keyword(s):  
Noise Control ◽  
Broad Band ◽  
Phononic Crystals ◽  
Frequency Noise ◽  
Band Frequency

Study on Locally Resonant Phononic Crystals Based on Automotive Noise Control

2011 ◽  
Vol 299-300 ◽  
pp. 1208-1211
Author(s):  
Yu Yang He ◽  
Xiao Xiong Jin ◽  
Huan Wei
Keyword(s):  
Band Gap ◽  
Noise Control ◽  
Low Frequency ◽  
Simulation Method ◽  
Phononic Crystals ◽  
Simplified Model ◽  
Frequency Noise ◽  
Two Dimensional ◽  
Low Frequency Noise ◽  
The Impact

Automotive low frequency noise is difficult to control in a traditional way. Locally resonant phononic crystals (PCs) can forbid the propagation of certain frequency. This PCs’ structure also can be fabricated to apply in automotive noise control. The simulation method is applied to establish the model of two-dimensional (2D) locally resonant phononic crystals in order to research the impact of the parameters on the propagation. The band gap of locally resonant phononic crystals in z mode is calculated using the simplified model.

Noise Sources and Transmission in Piping Systems

2002 ◽  
Author(s):  
Stephen A. Hambric ◽  
Yun Fan Hwang ◽  
Thomas S. Chyczewski
Keyword(s):  
Vibrational Energy ◽  
Broad Band ◽  
Computational Cost ◽  
Piping System ◽  
Frequency Noise ◽  
Energy Propagation ◽  
Acoustic Attenuation ◽  
Noise Sources ◽  
Band Frequency ◽  
Piping Systems

An overview of the vibro-acoustic behavior of fluid-filled piping systems is given, summarizing noise sources, how piping structures and fluids accept energy from noise sources, and how the energy is then transmitted and exchanged by wavetypes throughout the piping. Discrete and broad-band frequency noise sources from active components, such as pumps, and passive components, such as valves and flow over piping, are described, and scale on flow velocities and operating speeds. The turbulence in the fluid flow contributes to piping system noise and vibration. The turbulence in the core flow impinges on both active and passive devices, causing discrete and broad-band noise sources. Turbulence near pipe walls excites structural piping modes. Techniques for quantifying the turbulence and its effects are described. An overview of the mechanisms of acoustic and vibrational energy propagation in piping walls and fluids is given, along with a discussion of various tools used to model the propagation, such as finite element (FE) and boundary element (BE) analysis, transfer matrix (TM) analysis, and statistical energy analysis (SEA). FE and BE models may be used to model high levels of complexity in both structural-acoustic systems and noise sources, but require large model sizes at high frequencies. TM and SEA models sacrifice modeling generality, but can represent high frequency behavior at low computational cost. Finally, means of mitigating acoustic and vibration energy transmission, such as narrow-band acoustic attenuation devices (quarter wavelength silencers and Quincke tubes), broad-band acoustic attenuation devices (mufflers and acoustic filters), and broad-band structural vibration attenuation devices (isolators and rubber piping), are outlined.

scholarly journals Acoustic notch filtering earmuff utilizing Helmholtz resonator arrays

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258842
Author(s):  
Fumiya Mizukoshi ◽  
Hidetoshi Takahashi
Keyword(s):  
Resonant Frequency ◽  
Noise Control ◽  
Active Noise Control ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Honeycomb Structure ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Target Frequency ◽  
Notch Filtering

In recent years, noisy bustling environments have created situations in which earmuffs must soundproof only specific noise while transmitting significant sounds, such as voices, for work safety and efficiency. Two sound insulation technologies have been utilized: passive noise control (PNC) and active noise control (ANC). However, PNC is incapable of insulating selective frequencies of noise, and ANC is limited to low-frequency sounds. Thus, it has been difficult for traditional earmuffs to cancel out only high-frequency noise that people feel uncomfortable hearing. Here, we propose an acoustic notch filtering earmuff utilizing Helmholtz resonator (HR) arrays that provides a sound attenuation effect around the tuneable resonant frequency. A sheet-like sound insulating plate comprising HR arrays is realized in a honeycomb structure. Since the resonant frequency is determined by the geometry of the HR arrays, a highly audible sound region can be designed as the target frequency. In this research, the acoustic notch filtering performance of the proposed HR array plate is investigated in both simulations and experiments. Furthermore, the fabricated earmuffs using the novel HR array plates achieve a sound insulation performance exceeding 40 dB at the target frequency, which is sufficiently high compared to that of conventional earmuffs. The experimental results confirm that the proposed device is a useful approach for insulating frequency-selective sound.

Low-frequency noise control using layered granular aerogel and limp porous media

2021 ◽  
Vol 263 (4) ◽  
pp. 2724-2729
Author(s):  
Yutong Xue ◽  
Amrutha Dasyam ◽  
J. Stuart Bolton ◽  
Bhisham Sharma
Keyword(s):  
Noise Control ◽  
Glass Fibers ◽  
Low Frequency ◽  
Normal Incidence ◽  
Frequency Noise ◽  
Fibrous Materials ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Fibrous Media ◽  
Impedance Tube Method

The acoustic absorption of granular aerogel layers with a granule sizes in the range of 2 to 40 μm is dominated by narrow-banded, high absorption regions in the low-frequency range and by reduced absorption values at higher frequencies. In this paper, we investigate the possibility of developing new, low-frequency noise reduction materials by layering granular aerogels with traditional porous sound absorbing materials such as glass fibers. The acoustic behavior of the layered configurations is predicted using the arbitrary coefficient method, wherein the granular aerogel layers are modeled as an equivalent poro-elastic material while the fibrous media and membrane are modeled as limp media. The analytical predictions are verified using experimental measurements conducted using the normal incidence, two-microphone impedance tube method. Our results show that layered configurations including granular aerogels, fibrous materials, and limp membranes provide enhanced sound absorption properties that can be tuned for specific noise control applications over a broad frequency range.

scholarly journals Study of a Nonlinear Membrane Absorber Applied to 3D Acoustic Cavity for Low Frequency Broadband Noise Control

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1138 ◽  
Author(s):  
Jianwang Shao ◽  
Tao Zeng ◽  
Xian Wu
Keyword(s):  
Degrees Of Freedom ◽  
Noise Control ◽  
Normal Modes ◽  
Low Frequency ◽  
Harmonic Balance Method ◽  
Nonlinear Normal Modes ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Acoustic Cavity ◽  
Nonlinear Membrane

As a new approach to passive noise control in low frequency domain, the targeted energy transfer (TET) technique has been applied to the 3D fields of acoustics. The nonlinear membrane absorber based on the TET can reduce the low frequency noise inside the 3D acoustic cavity. The TET phenomenon inside the 3D acoustic cavity has firstly investigated by a two degrees-of-freedom (DOF) system, which is comprised by an acoustic mode and a nonlinear membrane without the pre-stress. In order to control the low frequency broadband noise inside 3D acoustic cavity and consider the influence of the pre-stress for the TET, a general model of the system with several acoustic modes of 3D acoustic cavity and one nonlinear membrane is built and studied in this paper. By using the harmonic balance method and the numerical method, the nonlinear normal modes and the forced responses are analyzed. Meanwhile, the influence of the pre-stress of the nonlinear membrane for the TET is investigated. The desired working zones of the nonlinear membrane absorber for the broadband noise are investigated. It can be helpful to design the nonlinear membrane according the dimension of 3D acoustic cavity to control the low frequency broadband noise.

scholarly journals Plate-Type Acoustic Metamaterials: Experimental Evaluation of a Modular Large-Scale Design for Low-Frequency Noise Control

Acoustics ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 354-368 ◽  
Author(s):  
Linus Ang ◽  
Yong Koh ◽  
Heow Lee
Keyword(s):  
Large Scale ◽  
Noise Control ◽  
Traffic Noise ◽  
Low Frequency ◽  
Industrial Applications ◽  
Frequency Noise ◽  
Acoustic Metamaterials ◽  
Scale Design ◽  
Stress Uniformity ◽  
Plate Type

For industrial applications, the scalability of a finalised design is an important factor to consider. The scaling process of typical membrane-type acoustic metamaterials may pose manufacturing challenges such as stress uniformity of the membrane and spatial consistency of the platelet. These challenges could be addressed by plate-type acoustic metamaterials with an internal tonraum resonator. By adopting the concept of modularity in a large-scale design (or meta-panel), the acoustical performance of different specimen configurations could be scaled and modularly combined. This study justifies the viability of two meta-panel configurations for low-frequency (80–500 Hz) noise control. The meta-panels were shown to be superior to two commercially available noise barriers at 80–500 Hz. This superiority was substantiated when the sound transmission class (STC) and the outdoor-indoor transmission class (OITC) were compared. The meta-panels were also shown to provide an average noise reduction of 22.7–27.4 dB at 80–400 Hz when evaluated in different noise environments—traffic noise, aircraft flyby noise, and construction noise. Consequently, the meta-panel may be further developed and optimised to obtain a design that is lightweight and yet has good acoustical performance at below 500 Hz, which is the frequency content of most problematic noises.

Distributed broad-band frequency translator and its use in a 1-3-GHz coherent reflectometer

1998 ◽  
Vol 46 (12) ◽  
pp. 2244-2250 ◽  
Author(s):  
P. Akkaraekthalin ◽  
S. Kee ◽  
D.W. Van Der Weide
Keyword(s):  
Broad Band ◽  
Band Frequency
Sign in / Sign up

Export Citation Format

Share Document