Small plate vibration sound-absorbing device with a clearance and without surrounding restriction: Theoretical analysis and experiment

2021 ◽  
Vol 69 (1) ◽  
pp. 30-38
Author(s):  
Shuichi Sakamoto ◽  
Kouhei Fujisawa ◽  
Shunsuke Watanabe ◽  
Taku Watanabe ◽  
Ryota Kominami ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Sound Absorption ◽  
Helmholtz Resonator ◽  
Plate Vibration ◽  
Frequency Range ◽  
Small Vibration ◽  
Electrical Equivalent Circuit ◽  
Architectural Acoustics ◽  
Absorbing Material ◽  
Conventional Plate

This article focuses on the theoretical analysis and experiment of a small plate vibration sound-absorbing device with a clearance and without surrounding restriction. Generally, a plate vibration sound-absorbing device absorbs sound in a frequency range lower than that of porous material, which is used as a sound-absorbing material, and its sound absorption coefficient is small. Furthermore, note that the plate is fixed at the periphery in a conventional plate vibration sound-absorbing device. Hence, when the plate is small, vibration barely occurs and effective sound-absorbing effect is not obtained. Given that the plate vibration sound-absorbing device has a restriction wherein a particular size of plate is required, it is primarily utilized for indoor finishing considering the architectural acoustics, and finding applications for small-sized machines has been challenging. Theoretical values in this work are calculated assuming that the clearance and back air layer for the small plate vibration sound-absorbing device constitute a Helmholtz resonator. Furthermore, experiments were conducted to perform comparisons against the theoretical value. The theoretical analysis was conducted by connecting the clearance and back air layer in parallel with the plate portion in the electrical equivalent circuit. By performing the experiments using various parameters, the sound absorption characteristics of the proposed plate vibration sound-absorbing device were determined. If the clearance is smaller than the boundary layer thickness, then the conventional resistive end correction cannot be applied.

scholarly journals Influence of Sugar Palm Ash Fraction and Resonator Configuration on Acoustic Absorption Performance of Expose Brick

2016 ◽  
Vol 4 (01) ◽  
pp. 19
Author(s):  
Zulfa Kamila R ◽  
Iwan Yahya ◽  
Utari U
Keyword(s):  
Performance Improvement ◽  
Performance Optimization ◽  
Sound Absorption ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Raw Material ◽  
Frequency Range ◽  
Helmholtz Resonators ◽  
Resonator Structure ◽  
Absorption Performance

<span>Sound absorption performance optimization of expose brick has been conducted in associated with <span>the fraction of sugar palm ash in its raw material and configuration of Helmholtz resonators inside <span>the brick structure. The testing was conducted experimentally refer to ASTM E-1050-98 standard <span>procedure. In this case there are three variations sugar palm ash fractions of 0%, 5%, and 10%, as <span>well as two array resonator configurations. The results showed that the brick with fraction of 10% <span>sugar palm ash has the best sound absorption performance. As for the configuration of array <span>identical Helmholtz resonator giving better performance improvement at low frequency span than <span>complex resonator structure with coupled cavity where the best performance occur on(376-488) <span>Hz frequency range with the absorption coefficient α of 0.54.</span></span></span></span></span></span></span></span><br /></span>

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

The theoretical analysis and simulation of acoustic absorber for nonlinear shunted loudspeaker

2021 ◽  
Vol 263 (6) ◽  
pp. 388-393
Author(s):  
Wenjiang Wang ◽  
Xianhui Li ◽  
Junjuan Zhao ◽  
Peng Zhang ◽  
Xinyun Li ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Sound Absorption ◽  
Nonlinear Term ◽  
Equivalent Model ◽  
Frequency Bandwidth ◽  
Nonlinear Circuit ◽  
Van Der Pol ◽  
Absorption Bandwidth ◽  
Simulation Results ◽  
Different Time Scales

In this paper, a nonlinear electroacoustic absorber based on a tunable loudspeaker is proposed to broaden its sound absorption bandwidth. The main mechanism is a nonlinear circuit is coupled at loudspeaker's terminal. A series of theoretical analysis and simulation work are carried out in this paper. The equivalent model is composed of a linear term describing the loudspeaker and a nonlinear term of a coupled Duffing-van Der Pol bistable circuit. The invariant manifold method is used to solve different time scales. The analysis and simulation results show that the nonlinear circuit can widen the frequency bandwidth of the structure.

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

2013 ◽  
Vol 38 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Dariusz Pleban
Keyword(s):  
Sound Absorption ◽  
Free Field ◽  
Tone Burst ◽  
Mineral Wool ◽  
Frequency Range ◽  
Absorption Properties ◽  
Open Cell Foam ◽  
Properties Of Materials ◽  
Cell Foam

Abstract Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Design and simulation of Helmholtz resonator assembly used to attenuate tire acoustic cavity resonance noise

2021 ◽  
Vol 263 (6) ◽  
pp. 942-953
Author(s):  
Wei Zhao ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Tian He
Keyword(s):  
Natural Frequencies ◽  
Helmholtz Resonator ◽  
Operating Conditions ◽  
Cavity Resonance ◽  
Frequency Range ◽  
Sound Fields ◽  
Acoustic Cavity ◽  
The Poor ◽  
Alloy Wheel ◽  
Reduction Effect

Tire acoustic cavity resonance noise (TACRN) is a typical annoying lower-frequency interior noise of a passenger car. The widely used attenuating method of attaching the porous sound absorption material in tire cavity can reduce TACRN effectively, but causes the increase of tire-wheel assembly weight and cost, also the poor durability. Additionally, the Helmholtz resonator (HR) is also used in the wheel of some cars although having only narrow effective band. The existing investigation shows that the frequency of TACRN varies with the car speed and load and also has the split characteristics. The change of TACRN frequency causes a certain difficulty to suppress TACRN effectively. Aiming at this problem, in this paper, TACRN frequency range of a specific tire cavity under different operating conditions is first calculated and analyzed. Then, for a specific aluminum alloy wheel, a HR assembly including several HRs is designed to make the natural frequencies of HR assembly cover the TACRN frequencies. Finally, the reduction effect of TACRN is simulated and evaluated by comparing the sound fields in tire cavity with/without HR assembly under same volume velocity sound source. This work is helpful for attenuating TACRN effectively under the changing operating conditions.

Utilization of Styrofoam ss Soundproofing Material with Auditory Frequency Range

2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Sjahrul Meizar Nasri ◽  
Iting Shofwati
Keyword(s):  
Hearing Loss ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Noise Exposure ◽  
Preventive Action ◽  
Frequency Range ◽  
Acoustical Property ◽  
Noise Barrier ◽  
Polystyrene Waste ◽  
Action Methods

One of preventive action methods of hearing loss that number tend to increase is by using brick that made from Styrofoam which is expected to have the ability as a soundproof that can be used to control the noise. The aim of this research is to assess the use of sound absorption material in which utilizing Styrofoam to reduce the noise exposure. In this study, cement and find aggregate that contain the Styrofoam and sand are mixed with the composition 1:4 and 1:6 and also by adding the polystyrene waste as much as 0%, 20%, 40%, 60%, and 80%.  To determine the acoustical property of the mixture, the sound absorbing coefficient (α) was determined by using Four Microphones Impedance Tube (ISO 140-3). The results showed that the highest absorption coefficient value was at frequency 800 Hz by adding 80% Styrofoam for the composition of 1:4 at 0.4100 dB and at the frequency 800 Hz by adding 40% Styrofoam for the composition 1:6 at 0.5870 dB. Based on the results of this research, further study to potentially use Styrofoam as noise barrier is suggested.

USE OF CORK SHEETS FOR ROOM ACOUSTIC CORRECTION

2020 ◽  
Vol 15 (2) ◽  
pp. 45-55
Author(s):  
Gino Iannace ◽  
Giuseppe Ciaburro ◽  
Luigi Guerriero ◽  
Amelia Trematerra
Keyword(s):  
Sound Absorption ◽  
Rigid Wall ◽  
Virtual Model ◽  
Rear Wall ◽  
Acoustic Characteristics ◽  
Architectural Acoustics ◽  
Acoustic Comfort ◽  
Useful Life ◽  
Correction System

ABSTRACT Cork is a sustainable material and at the end of its useful life it can be disposed of into the environment without causing damage. This paper analyzes an acoustic correction system made of cork sheets mounted at an opportune distance from the walls inside a room. The cork sheets have a thickness equal to 1.5 mm. The sound absorption coefficients of the cork sheets were initially evaluated by mounting samples inside an impedance tube, then creating a back cavity at a suitable distance from a rigid wall. The distances considered were: 3, 5, 10 and 15 cm. A room used as an office with a volume of about 90 m3 and plastered walls was considered as a case-study. In this type of environment, suitable acoustic comfort conditions are required. The acoustic characteristics were analyzed through a virtual model with an architectural acoustics software in an empty room and then with the introduction of sound-absorbing cork sheets. Measurements of the acoustic characteristics of the empty room were taken and subsequently with the walls lined with cork panels mounted at a distance of 3.0 cm from the rigid rear wall. A configuration was analyzed, in line with what was carried out in the numerical model, covering a surface of 5m2 of the room. The results of the numerical simulations as well as the experimental measurements are discussed.

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