scholarly journals Virgin Natural Cork Characterization as a Sustainable Material for Use in Acoustic Solutions

2021 ◽  
Vol 13 (9) ◽  
pp. 4976
Author(s):  
Juan Miguel Barrigón Morillas ◽  
David Montes González ◽  
Rosendo Vílchez-Gómez ◽  
Valentín Gómez Escobar ◽  
Rubén Maderuelo-Sanz ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Scientific Literature ◽  
Outer Bark ◽  
Reverberation Chamber ◽  
Frequency Bands ◽  
Sustainable Material ◽  
Natural Cork ◽  
Sheep Wool

A characterization of the sound absorption of a sustainable material with scarce current use such as natural virgin cork is presented in this paper in order to explore further possible applications in the design of acoustic solutions. Different samples of virgin cork not bonded and various decorative panel formats were tested under random sound incidence conditions in a standardized reverberation chamber. The samples in which the outer bark of the cork was facing upwards showed a better behavior as an acoustic absorber, with sound absorption coefficient values generally greater than 0.6 for frequency bands between 1 and 5 kHz. The results obtained were compared with samples of some recycled materials available in the scientific literature, such as sheep wool and PET.

Development of Sound Absorbers for Large Spaces

2005 ◽  
Vol 12 (4) ◽  
pp. 237-254
Author(s):  
Yoshihito Kobayashi ◽  
Toshiya Kitamura ◽  
Shinji Yamada
Keyword(s):  
Absorption Coefficient ◽  
Resonance Frequency ◽  
High Frequency ◽  
Sound Absorption ◽  
Low Frequency ◽  
Frequency Bands ◽  
Sound Fields ◽  
Absorption Area ◽  
Translucent Material ◽  
The Chairs

Moulded chairs have been developed, in which sound absorption at low frequency bands is increased by using the seat section and/or the back section as a resonator. In addition, a translucent sound absorption panel has been developed for application in large spaces. In the case of the chairs the resonance frequency, determined by the position, number, and depth of the holes, was examined. Prototypes were constructed, and the equivalent absorption area was measured in a reverberation room. The resonators of the chairs achieved an equivalent absorption area of 0.15 m2/seat, in the 125 Hz band. For the case of the translucent material, sound absorption was measured and compared with conventional sound absorption materials. The panels were designed in order to control sound fields in large spaces. The panels achieved a sound absorption coefficient of 0.6 to 1.0 at middle and high frequency bands.

The Process Development for Sound Absorption Design of Non-Woven Car Mat

2020 ◽  
Vol 305 ◽  
pp. 43-48
Author(s):  
Un Hwan Park ◽  
Jun Hyeok Heo ◽  
In Sung Lee ◽  
Dae Kyu Park
Keyword(s):  
Absorption Coefficient ◽  
Physical Properties ◽  
Sound Absorption ◽  
Process Development ◽  
Sound Absorption Coefficient ◽  
Development Effort ◽  
Reverberation Chamber ◽  
Impedance Tube ◽  
Impedance Tubes ◽  
Automotive Interior

Automotive interior material with consists of several material layers has the sound-absorbing function. It is difficult to predict sound absorbing coefficient because of several material layers. So, many experimental tuning is required to achieve the target of sound absorption. Therefore, while the car interior materials are developed, a lot of time and money is spent. In this study, we present the method to predict the sound absorbing performance of the material with multi-layer using physical properties of each material. The properties are predicted by foam-X software using sound absorption coefficient data measured by impedance tube. And we will compare and analyze the predicted sound absorption coefficient with the data measured by scaled reverberation chamber and impedance tubes for a prototype. If the method is used instead of experimental tuning in the development of car interior material, the time and money can be saved. And then, the development effort can be is reduced because it can be optimized by simulation.

scholarly journals Characterization of Sheep Wool as a Sustainable Material for Acoustic Applications

Materials ◽  
2017 ◽  
Vol 10 (11) ◽  
pp. 1277 ◽  
Author(s):  
Romina del Rey ◽  
Antonio Uris ◽  
Jesús Alba ◽  
Pilar Candelas
Keyword(s):  
Sustainable Material ◽  
Sheep Wool

scholarly journals Measurements of the Sound Absorption Coefficient of Auditorium Seats for Various Geometries of the Samples

2012 ◽  
Vol 37 (4) ◽  
pp. 483-488 ◽  
Author(s):  
Jarosław Rubacha ◽  
Adam Pilch ◽  
Marcin Zastawnik
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Infinite Dimensions ◽  
Reverberation Chamber

Abstract This paper presents the results of measurements of the sound absorption coefficient of auditorium seats carried out in the laboratory using two methods. In the first one, small blocks of seats in various arrangements were studied in a reverberation chamber to determine the absorption coefficient of an auditorium of infinite dimensions. The results were compared to the values of the absorption coefficient measured using the second method, which involved samples enclosed within a frame screening the side surfaces of other auditorium blocks. The results of both methods allowed for the assessment of the sound absorption coefficient of an auditorium of any dimensions while taking into account the sound absorption by the side surfaces. The method developed by the authors will simplify the currently known measurement procedures.

Synthesis and Characterization of Epoxy Resin Reinforced with Luffa Fiber Composites for Sound Absorption

2014 ◽  
Vol 624 ◽  
pp. 36-41
Author(s):  
Elammaran Jayamani ◽  
Sinin Hamdan ◽  
M. Rezaur Rahman
Keyword(s):  
Absorption Coefficient ◽  
Epoxy Resin ◽  
Sound Absorption ◽  
Thermal Analyses ◽  
Thermal Characterization ◽  
Alkaline Treatment ◽  
Sound Absorption Coefficient ◽  
Morphological Aspect ◽  
Standing Wave Method

Now a day’s sustainable development becomes an increasingly significant goal in the evaluation and promotion of Industries. There is currently considerable interest in developing sustainable acoustic absorbers. This research aims to develop and characterize composite materials made of Epoxy resin reinforced with luffa fibres as sustainable acoustic absorbers. The fibres where chemically modified by alkaline treatment and its effects on the fibre-matrix interaction were also evaluated. The effect of chemical modification on fibre morphology was studied by Scanning electron microscope (SEM). Likewise, the sound absorption coefficient of composites were studied using 2 types of Impedance tube methods namely Two microphone transfer function and standing wave method. The thermal analyses of composites were made using Thermogravimetric analysis. The sound absorption coefficient of untreated and treated composites across a range of frequencies was very similar. To be more specific, untreated composites appeared to perform better than those of treated ones. After chemical modifications, the SEM characterization showed that the alkaline treatment changed the morphology of fibers, resulting in decrease in sound absorption coefficients of composites. This is probably due to the new morphological aspect. The thermal characterization of composites shows that dehydration and degradation of lignin occurred around 40 - 260°C and maximum percentage cellulose was found to decompose at 380°C.

scholarly journals Effect of Diffusion Conditions on Absorption Performance of Materials Evaluated in Reverberation Chamber

2019 ◽  
Vol 11 (23) ◽  
pp. 6651
Author(s):  
Kyung Ho Kim ◽  
Jin Yong Jeon
Keyword(s):  
Absorption Coefficient ◽  
Edge Effect ◽  
Sound Absorption ◽  
Specimen Surface ◽  
Sound Absorption Coefficient ◽  
Accurate Estimation ◽  
Reverberation Chamber ◽  
Evaluation Indicator ◽  
Relative Standard ◽  
Absorption Performance

Obtaining the reverberation time of a multipurpose building is most effective when accurate data is used to simulate the building. Therefore, this study proposes a method of measuring the sound absorption coefficient that is close to the sound absorption performance of the conditions in which building materials are actually used. In addition, a sufficient diffusivity evaluation method for sound absorption coefficient measurement in a reverberation chamber is proposed, to address the sound absorption performance difference caused by internal diffusion of the reverberation chamber. When the sound absorption performance was evaluated after installing the specimen under the condition of minimized edge effect, the result obtained should closely match the sound absorption performance of the specimen surface. The sound absorption performance of the specimen ( α β E ≈ 0 ) with minimized edge effect and the sound absorption performance on the specimen surface ( α ∞ ) were proposed as an evaluation indicator of agreement between the values. Experimental results show that diffusion inside the reverberation chamber is enhanced when α ∞ − α β E ≈ 0 < 0.02, for which sufficient diffusion can be assumed inside the reverberation chamber. In addition, to verify the validity of the proposed evaluation indicator, we investigated the relationship with the objective diffusion evaluation indicator for diffuse field configuration in the reverberation chamber, such as relative standard deviation of decay rate ( S r e l ) and Np values. The results of this study are expected to contribute to a more accurate estimation of the sufficient diffusion condition in the reverberation chamber, in evaluating the sound absorption performance of the material, and that inside the reverberation chamber.

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).

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