Improvement and Change of Acoustic Performance of MRI Room by Changing Sound Absorption Factor

2018 ◽  
Vol 19 (2) ◽  
pp. 129-138
Author(s):  
Hee La Jang ◽  
Hyun Jae Lee ◽  
Jae Soo Kim
Keyword(s):  
Sound Absorption ◽  
Absorption Factor ◽  
Acoustic Performance

scholarly journals Sound Absorption Properties of Aluminum Sponges Manufactured by Infiltration Process

2010 ◽  
Vol 146-147 ◽  
pp. 1651-1654 ◽  
Author(s):  
Patricia M. Fernández ◽  
Luis J.R. Cruz ◽  
Luis E. García Cambronero ◽  
Cesar Díaz ◽  
María Ángeles Navacerrada
Keyword(s):  
Pore Size ◽  
Sound Absorption ◽  
Frequency Range ◽  
Absorption Factor ◽  
Absorption Properties ◽  
Infiltration Process ◽  
Interconnected Porosity ◽  
Factor Α

In this paper, the sound absorption properties of aluminum sponges manufactured by infiltration process have been studied. The results show that the sound absorption factor α changes in function of pore size. Additionally, the sound absorption factor α was sensitive to the frequency range measured and it was depending of the thickness sample. It was found that the interconnected porosity plays an important role increasing the sound absorption properties of the aluminum sponges studied.

scholarly journals Investigation on the acoustic properties of structural gradient 316L stainless steel hollow spheres composites

2021 ◽  
Vol 28 (1) ◽  
pp. 478-488
Author(s):  
Chunhe Wang ◽  
Chunhuan Guo ◽  
Fengchun Jiang
Keyword(s):  
Stainless Steel ◽  
Sound Absorption ◽  
316L Stainless Steel ◽  
Hollow Spheres ◽  
Acoustic Properties ◽  
Casting Method ◽  
Acoustic Performance ◽  
A356 Aluminum ◽  
Different Diameters ◽  
Scanning Electron

Abstract In this study, a kind of structural gradient metal hollow spheres composites (SG-MHSCs) were fabricated using two kinds of 316L stainless steel hollow spheres with different diameters and A356 aluminum through the casting method. Then the density of the SG-MHSCs was measured by the direct measurement; the microstructure of the SG-MHSCs was characterized by the Scanning Electron Microscope. Meanwhile, the acoustic performance of MHSCs was tested by the impedance tube, and the sound absorption and insulation mechanism SG-MHSCs were discussed and analyzed.

scholarly journals Development and Investigation of Fully Ventilated Deep Subwavelength Absorbers

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1835
Author(s):  
Heng Wang ◽  
Qibo Mao
Keyword(s):  
Theoretical Model ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Metamaterial ◽  
Acoustic Performance ◽  
Half Wave ◽  
Quarter Wave ◽  
New Type ◽  
Good Agreement

A new type of deep subwavelength acoustic metamaterial (AMM) absorber with 100% ventilation is presented in this study. The proposed ventilation absorber consists of coiled-up half-wave resonators (HWRs) and quarter-wave resonators (QWRs). First, the sound absorption and sound transmission performances for absorbers were analyzed considering the thermal viscosity dissipation. Then, the prototype with ten HWRs and three QWRs composed of acrylic plates was manufactured based on the theoretical model. The acoustic performance of the absorber was tested in an air-filled acoustic impedance tube to determine the sound absorption and transmission loss performances. Good agreement was found between the measured and theoretically predicted results. The experimental results show that the proposed ventilation AMM absorber is able to achieve sound absorption in a range between 330 Hz and 460 Hz with a thickness of only 32 mm (about 3% of the wavelength in the air). Furthermore, the sound transmission loss can achieve 17 dB from 330 Hz to 460 Hz. The main advantage of the proposed absorber is that it can be completely ventilated in duct noise control.

Acoustic performance prediction of anechoic layer using identified viscoelastic parameters

2018 ◽  
Vol 25 (6) ◽  
pp. 1164-1178 ◽  
Author(s):  
Meng Tao ◽  
Hanfeng Ye ◽  
Xuefeng Zhao
Keyword(s):  
Performance Prediction ◽  
Sound Absorption ◽  
Oblique Incidence ◽  
Cylindrical Tube ◽  
The Other ◽  
Reflection Coefficients ◽  
Dynamic Parameters ◽  
Acoustic Performance ◽  
Viscoelastic Parameters ◽  
Cylindrical Holes

In this work, the acoustic performance of an anechoic layer, which contains horizontally-distributed cylindrical holes, has been studied using identified viscoelastic dynamic parameters. First, the reflection coefficients of two different viscoelastic anechoic layers (one solid and the other perforated), tested in a water-filled pipe, have been used to develop the identification method for viscoelastic dynamic parameters. In the proposed method, the complex longitudinal wavenumber and the complex transverse wavenumber can be obtained by solving the characteristic equation of viscoelastic cylindrical tube. Then, simulations have been performed using COMSOL software to predict the acoustic performance of the anechoic layer. Based on the model and the identified viscoelastic parameters, the effects of different structural properties, including the radius of hole, the hole horizontal spacing, and the arrangements of holes, on the sound absorption of anechoic layer have been analyzed and discussed. Particularly, the acoustic performance of an anechoic layer under oblique incidence has also been considered.

scholarly journals A Parametric Study of the Acoustic Performance of Resonant Absorbers Made of Micro-perforated Membranes and Perforated Panels

2020 ◽  
Vol 10 (5) ◽  
pp. 1581 ◽  
Author(s):  
Lili Pan ◽  
Francesco Martellotta
Keyword(s):  
Sound Absorption ◽  
Parametric Optimization ◽  
Prediction Models ◽  
Measured Data ◽  
Mechanical Resistance ◽  
Ideal Solution ◽  
Visual Contact ◽  
Acoustic Performance ◽  
Optically Transparent ◽  
The Ideal

Sound absorbing surfaces are being increasingly requested for the acoustical treatment of spaces, like offices and restaurants, where high aesthetic standards are requested. In these cases, perforated and micro-perforated panels may represent the ideal solution in terms of low maintenance, durability, and mechanical resistance. In addition, such a solution might be conveniently realized while using optically transparent panels, which might offer extra value, as they could ensure visual contact, while remaining neutral in terms of design. The paper first investigates the reliability of prediction models by comparison with measured data. Subsequently, while taking advantage of a parametric optimization algorithm, it is shown how to design an absorber covering three octave bands, from 500 Hz to 2 kHz, with an average sound absorption coefficient of about 0.8.

Acoustic Benefits of Ecofriendly Spent Tea Leaves Filled Porous Material

2017 ◽  
Vol 739 ◽  
pp. 125-134
Author(s):  
Kylie Wong ◽  
Qumrul Ahsan ◽  
Azma Putra ◽  
Sivarao Subramonian ◽  
Noraiham Mohamad ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
High Resistance ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Tea Plant ◽  
Sound Absorption Coefficient ◽  
Acoustic Performance ◽  
Absorbing Material ◽  
Tea Leaf

This paper demonstrates the feasibility of spent tea leaf (STL) fiber as an eco-friendly sound absorbing material. STL fiber is a by-product which was extracted from tea plant. STL are rich in polyphenols (tannins) which cause high resistance to fungal and termites, and high resistance to fire. In addition, STL are hollow and cellular in nature and thus perform well as acoustic and thermal insulators. Three different grades of STL were studied and the acoustic property was analyzed in terms of sound absorption coefficient and transmission loss. Experimental measurements of sound absorption coefficient in impedance tube are conducted. It was found that finest STL fiber grade exhibits better acoustic performance among others. Furthermore, the effect of latex binder on the acoustic property of STL fiber was also analyzed. Results suggest that the types of binder such as polyurethane and latex influenced the acoustic performance of STL fiber.

scholarly journals Thermal and acoustic insulation boards from microalgae biomass, poly-β-hydroxybutyrate and glass wool

2020 ◽  
Vol 9 (4) ◽  
pp. e143942995
Author(s):  
Eduardo Silveira Ribeiro ◽  
Ronan Adler Tavella ◽  
Guilherme Senna dos Santos ◽  
Felipe da Silva Figueira ◽  
Jorge Alberto Vieira Costa
Keyword(s):  
Sound Absorption ◽  
Glass Wool ◽  
Simultaneous Application ◽  
Insulating Materials ◽  
Acoustic Performance ◽  
Acoustic Insulation ◽  
Microalgae Biomass ◽  
Reduction Coefficient ◽  
The Many ◽  
Tea Leaf

Among the many functions that a building material needs to have, its insulation functions stand out. This type of materials acts by decreasing the conduction of heat/sound in to the environment. In this context, bio-insulations have been receiving an increasing attention due to its performance and the use of sustainable/naturals insulation materials. This study was conducted to evaluate the thermal and acoustic performance of bio-based boards made from the biomass of Spirulina, bacterial poly-β-hydroxybutyrate (PHB), and glass wool. The boards were manufactured under heated compression in different proportions: 33.33% glass wool, 33.33% PHB, and 33.33% Spirulina biomass (Board A); 20% glass wool, 40% PHB, and 40% Spirulina (Board B); 40% glass wool, 40% PHB, and 20% Spirulina (Board C); and 40% glass wool, 20% PHB, and 40% Spirulina (Board D). Boards A and B showed lower thermal conductivity (0.09 W m-1 K-1) compared to traditional insulating materials, such as gypsum neat (0.44 W m-1 K-1) and Kaolin insulating firebrick (0.08–0.19 W m-1 K-1). Board D showed the highest sound absorption coefficient of ~1600 Hz compared to other bio-based insulators at the same frequency, such as polypropylene based non-woven fiber and tea-leaf-fiber with the same thickness. For the noise reduction coefficient, board B showed better results than concrete. Thus, boards A and B are suitable as thermal insulators, while boards B and D are suitable as sound insulators. For simultaneous application as a thermal and sound insulator, board B is the best choice among all boards.

PRELIMINARY STUDY ON THE SOUND ABSORPTION BEHAVIOR OF SPENT TEA LEAVES FILLED WITH NATURAL RUBBER LATEX BINDER

2017 ◽  
Vol 79 (5-2) ◽  
Author(s):  
Kylie Wong ◽  
Qumrul Ahsan ◽  
Azma Putra ◽  
Sivarao Subramonian ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Sound Absorption ◽  
Natural Fibers ◽  
Natural Rubber Latex ◽  
Acoustic Property ◽  
Tea Plant ◽  
Extractive Content ◽  
Potential Hazard ◽  
Synthetic Fibers ◽  
Acoustic Performance ◽  
Absorbing Material

Nowadays, sound control has been regarded as one of the important requirements for human comfort. For an instance, control of room acoustic enables the room to achieve a good auditive environment for effective speech deliverance and presentations. Synthetic fibers such as glass wool fiber are commonly used for sound absorption. Over the years, it was discovered that synthetic fibers are expensive and possess potential hazard to environment and human health. Therefore, growing attention has been turned to natural fibers as an alternative to synthetic fibers. This paper demonstrates the feasibility of spent tea leaf (STL) fiber as an eco-friendly sound absorbing material. STL fiber is a by-product which was extracted from tea plant. It is unique with fresh aroma and rich in phenolic extractive content. Three different grades of STL fiber were studied and the acoustic property was analyzed in terms of sound absorption coefficient (SAC). Results showed that all the samples obtained maximum SAC above 0.70 at frequency range of 1993-3861 Hz. Furthermore, it was found that finest STL fiber grade exhibits better acoustic performance among others with a maximum SAC of 0.88 at 1993 Hz. Besides, the effect of latex binder on the acoustic property of STL fiber was also analyzed. Results suggest that the types of latex binder did not influence the acoustic performance of STL fiber. The overall results indicate that STL fiber can be a promising environment-friendly sound absorbing material.

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