Normal incidence sound absorption coefficient measurement using sound intensity technique: An accuracy investigation

1999 ◽  
Vol 106 (4) ◽  
pp. 2232-2232
Author(s):  
Mohamad N. Dimon ◽  
Ahmad K. Said ◽  
Md. N. Ibrahim ◽  
Md. Y. Jaafar
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Intensity ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Coefficient Measurement

COMPARISON OF NORMAL INCIDENT SOUND ABSORPTION COEFFICIENT OF DIRECT PIERCING CARVED WOOD PANEL FOR CIRCULAR, GEOMETRY AND FLORAL DESIGN

2016 ◽  
Vol 78 (6-10) ◽  
Author(s):  
Mohd Zamri Jusoh ◽  
Nazli Che Din ◽  
Mohamad Ngasri Dimon
Keyword(s):  
Boundary Element Method ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Intensity ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Wood Panel ◽  
High Frequencies ◽  
Wood Carving ◽  
Circular Design

Direct Piercing Carved Wood Panel (DPCWP) is among the famous Malay wood carving art in the Malay culture. It is the best example of Malay people’s creativity and masterpiece. In this paper, the comparison of normal incidence sound absorption coefficient,  (SAC) for three major types of design for the DPCWP is discussed. The simplest form of DPCWP, the circular type, then the geometry and floral types were investigated based on simulation and measurement works using sound intensity method to determine the normal incidence SAC, for 30% and 40% perforation ratios. The simulation work was carried out by using BEASY Acoustic software based on Boundary Element Method (BEM). From the results, there is an identical trend for DPCWP with geometry and floral design from 250 Hz to 4 kHz. At high frequencies (1 kHz to 4 kHz), both design show the tendency of decrement, suggesting that the complexity of the design does affect the average SAC value. However, for circular design, SAC is higher than other design at 1 kHz and shows a similar trend with other design at 2 kHz and 4 kHz for both simulation and measurement result.

scholarly journals Extrusion Foaming of Lightweight Polystyrene Composite Foams with Controllable Cellular Structure for Sound Absorption Application

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 106 ◽  
Author(s):  
Yanpei Fei ◽  
Wei Fang ◽  
Mingqiang Zhong ◽  
Jiangming Jin ◽  
Ping Fan ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Cellular Structure ◽  
Sound Absorption ◽  
Lignin Content ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Multiwall Carbon Nanotube ◽  
Nucleation Effect ◽  
Composite Foams ◽  
Extrusion Foaming

Polymer foams are promising for sound absorption applications. In order to process an industrial product, a series of polystyrene (PS) composite foams were prepared by continuous extrusion foaming assisted by supercritical CO2. Because the cell size and cell density were the key to determine the sound absorption coefficient at normal incidence, the bio-resource lignin was employed for the first time to control the cellular structure on basis of hetero-nucleation effect. The sound absorption range of the PS/lignin composite foams was corresponding to the cellular structure and lignin content. As a result, the maximum sound absorption coefficient at normal incidence was higher than 0.90. For a comparison, multiwall carbon nanotube (MWCNT) and micro graphite (mGr) particles were also used as the nucleation agent during the foaming process, respectively, which were more effective on the hetero-nucleation effect. The mechanical property and thermal stability of various foams were measured as well. Lignin showed a fire retardant effect in PS composite foam.

Sound Absorption Characteristics of Porous Steel Manufactured by Lost Carbonate Sintering

2009 ◽  
Vol 1188 ◽  
Author(s):  
Miao Lu ◽  
Carl Hopkins ◽  
Yuyuan Zhao ◽  
Gary Seiffert
Keyword(s):  
Absorption Coefficient ◽  
Pore Size ◽  
Sound Absorption ◽  
Single Layer ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Impedance Tube ◽  
Absorption Characteristics

AbstractThis paper investigates the sound absorption characteristics of porous steel samples manufactured by Lost Carbonate Sintering. Measurements of the normal incidence sound absorption coefficient were made using an impedance tube for single-layer porous steel discs and assemblies comprising four layers of porous steel discs. The sound absorption coefficient was found not to vary significantly with pore size in the range of 250-1500 μm. In general, the absorption coefficient increases with increasing frequency and increasing thickness, and peaks at specific frequencies depending on the porosity. An increase in porosity tends to increase the frequency at which the sound absorption coefficient reaches this peak. An advantage was found in using an assembly of samples with gradient porosities of 75%-70%-65%-60% as it gave higher and more uniform sound absorption coefficients than an assembly with porosities of 75%.

Sound absorption coefficient measurement by extracting the first reflected wave in a short tube

2020 ◽  
Vol 159 ◽  
pp. 107087 ◽  
Author(s):  
Zhengyu Wei ◽  
Hong Hou ◽  
Nansha Gao ◽  
Yunke Huang ◽  
Jianhua Yang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Reflected Wave ◽  
Coefficient Measurement ◽  
Short Tube
Sign in / Sign up

Export Citation Format

Share Document