scholarly journals High sound absorption characteristics of foamed alumina ceramics fabricated by gelcasting-foaming process

2020 ◽  
Vol 128 (7) ◽  
pp. 387-394
Author(s):  
Guo-Rui LI ◽  
Chen-Hui LI ◽  
Jiang-An LIU ◽  
Yang ZOU ◽  
Liang HU ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Alumina Ceramics ◽  
Foaming Process ◽  
High Sound ◽  
Absorption Characteristics

scholarly journals Sound absorption characteristics of KGM-based aerogel

2020 ◽  
Vol 15 (3) ◽  
pp. 450-457
Author(s):  
Yixin Wang ◽  
Fei Xiang ◽  
Wei Wang ◽  
Weiling Wang ◽  
Yuehong Su ◽  
...  
Keyword(s):  
Pore Structure ◽  
Sound Absorption ◽  
Freeze Drying ◽  
Drying Method ◽  
Absorption Potential ◽  
Absorption Performance ◽  
Property Characterization ◽  
High Sound ◽  
Absorption Characteristics

Abstract This study presents the preparation and property characterization of biomass aerogels as sound absorption materials. Biomasses were chosen to prepare aerogels through the freeze-drying method. Results indicated that four components may have different effects on the aerogel pore structure, and the aerogel formula was thus optimized to reach the best sound absorption. Within the experimental range, biomass aerogel with the optimized formula had an average sound efficiency 0.352, density 0.047 g/cm3 and porosity 94.46 ± 0.04%. It shows better sound absorption performance than traditional sound absorption cotton. These results demonstrate the high sound absorption potential of biomass aerogels for building applications.

scholarly journals Bilayer ventilated labyrinthine metasurfaces with high sound absorption and tunable bandwidth

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiayuan Du ◽  
Yuezhou Luo ◽  
Xinyu Zhao ◽  
Xiaodong Sun ◽  
Yanan Song ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Air Flow ◽  
Single Layer ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Sound Barrier ◽  
Free Air ◽  
Relative Bandwidth ◽  
Wide Range ◽  
High Sound

AbstractThe recent advent of acoustic metamaterials offers unprecedented opportunities for sound controlling in various occasions, whereas it remains a challenge to attain broadband high sound absorption and free air flow simultaneously. Here, we demonstrated, both theoretically and experimentally, that this problem can be overcome by using a bilayer ventilated labyrinthine metasurface. By altering the spacing between two constituent single-layer metasurfaces and adopting asymmetric losses in them, near-perfect (98.6%) absorption is achieved at resonant frequency for sound waves incident from the front. The relative bandwidth of absorption peak can be tuned in a wide range (from 12% to 80%) by adjusting the open area ratio of the structure. For sound waves from the back, the bilayer metasurface still serves as a sound barrier with low transmission. Our results present a strategy to realize high sound absorption and free air flow simultaneously, and could find applications in building acoustics and noise remediation.

scholarly journals Sound absorption characteristics of a double-leaf structure with an MPP and a permeable membrane

2014 ◽  
Vol 76 ◽  
pp. 28-34 ◽  
Author(s):  
Kimihiro Sakagami ◽  
Yusaku Fukutani ◽  
Motoki Yairi ◽  
Masayuki Morimoto
Keyword(s):  
Sound Absorption ◽  
Leaf Structure ◽  
Permeable Membrane ◽  
Absorption Characteristics

Trial applications at gymnasiums of in-situ sound absorption measurement method by ensemble averaging technique

2021 ◽  
Vol 263 (2) ◽  
pp. 4532-4537
Author(s):  
Toru Otsuru ◽  
Reiji Tomiku ◽  
Noriko Okamoto ◽  
Siwat Lawanwadeekul
Keyword(s):  
Measurement Method ◽  
Sound Absorption ◽  
Glass Wool ◽  
Absorption Measurement ◽  
Ensemble Averaging ◽  
Averaging Technique ◽  
In Situ Conditions ◽  
Measurement Consistency ◽  
Absorption Characteristics

The authors have been published a series of papers on a measurement method for sound absorption characteristics of materials using ensemble averaging technique, i.e., EA method. The papers' results included measurement mechanisms, measurement uncertainty, and so on. Herein, to examine adaptability, especially in in-situ conditions, the EA method is applied to measure absorption characteristics of materials installed in two gymnasiums. A glass-wool panel with the dimension of 0.5 m by 0.5 m by 0.05 m and with the density of 32 kg m^-3 was brought around and measured to check the measurement consistency. Several measurements were conducted during badminton plays were undergoing. Measured sound absorption coefficients revealed that most results agree well with those measured in reverberation rooms. Certain improvement is necessary for the specimen brought to the in-situ measurement to keep the consistency. The inconsistency is considered to originate from unstable conditions between the specimen and floor.

scholarly journals Application of transparent microperforated panel to acrylic partitions for desktop use: A case study by prototyping

2021 ◽  
Author(s):  
Kimihiro Sakagami ◽  
Midori Kusaka ◽  
Takeshi Okuzono ◽  
Shigeyuki Kido ◽  
Daichi Yamaguchi
Keyword(s):  
Adverse Effect ◽  
Sound Absorption ◽  
Acoustic Environment ◽  
Actual Use ◽  
Acrylic Sheet ◽  
Absorption Performance ◽  
The Subject ◽  
Droplet Penetration ◽  
Absorption Characteristics

There are various measures currently in place to prevent the spread of COVID-19; however, in some cases, these can have an adverse effect on the acoustic environment in buildings. For example, transparent acrylic partitions are often used in eating establishments, meeting rooms, offices, etc., to prevent droplet infection. However, acrylic partitions are acoustically reflective; therefore, reflected sounds may cause acoustic problems such as difficulties in conversation or the leakage of conversation. In this study, we performed a prototyping of transparent acrylic partitions to which a microperforated panel (MPP) was applied for sound absorption while maintaining transparency. The proposed partition is a triple-leaf acrylic partition with a single acrylic sheet without holes between two MPP sheets, as including a hole-free panel is important to a possible droplet penetration. The sound absorption characteristics were investigated by measuring the sound absorption in a reverberation room. As the original prototype showed sound absorption characteristics with a gentle peak and low values due to the openings on the periphery, it was modified by closing the openings of the top and sides. The sound absorption performance was improved to some extent when the top and sides were closed, although there remains the possibility of further improvement. This time, only the sound absorption characteristics were examined in the prototype experiments. The effects during actual use will be the subject of future study.

scholarly journals Fabrication of cellulose-based aerogel for thermal and acoustic insulation applications

2021 ◽  
Vol 947 (1) ◽  
pp. 012030
Author(s):  
Ngan N T Thai ◽  
Quyen N D Chau ◽  
Nam D Do ◽  
Tuan D Tran ◽  
Ha K P Huynh ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Sound Absorption ◽  
Young Modulus ◽  
High Porosity ◽  
Water Contact ◽  
Acoustic Insulation ◽  
Conductivity Water ◽  
Oil Adsorption ◽  
High Sound ◽  
Absorption Measurements

Abstract A method to prepare aerogels from rice straw and polyvinyl alcohol in the presence of fiberglass and glutaraldehyde is herein reported. The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The obtained aerogels should be considered as a promising material for upcoming applications, since it has high porosity (up to 93.72%), low density (0.083-0.127 g/cm3), super low thermal conductivity (0.032-0.048 W/mK), high Young modulus (0.201-1.207 MPa), high sound absorption (absorption coefficient of 0.87) and a good oil adsorption capacity (4.8 g/g).

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