Comparison of three measurement techniques for the normal absorption coefficient of sound absorbing materials in the free field

2009 ◽  
Vol 126 (6) ◽  
pp. 3020-3027 ◽  
Author(s):  
Kunikazu Hirosawa ◽  
Kazuhiro Takashima ◽  
Hiroshi Nakagawa ◽  
Makoto Kon ◽  
Aki Yamamoto ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Measurement Techniques ◽  
Free Field ◽  
Absorbing Materials ◽  
Normal Absorption

Investigating the Effects of Fibrous Material Compression on the Acoustical Behavior of Absorption and Barrier Materials

2006 ◽  
Vol 129 (2) ◽  
pp. 133-140 ◽  
Author(s):  
A. R. Ohadi ◽  
M. Moghaddami
Keyword(s):  
Absorption Coefficient ◽  
Fibrous Material ◽  
Transmission Loss ◽  
Element Model ◽  
Physical Parameters ◽  
Fibrous Materials ◽  
Barrier Materials ◽  
Rigid Frame ◽  
Absorbing Materials ◽  
The Galerkin Method

This paper discusses the effects of compression on acoustical performance of fibrous materials. A finite element model is used to predict the absorption coefficient and transmission loss of absorbing and barrier materials. This model is developed based on the Galerkin method and includes the equation of wave propagation in rigid frame porous material. The compression of fibrous material is entered to the model with relations that explain modifications of physical properties used in the wave equation. Acoustical behavior of absorption and barrier materials with and without compression is studied. It is shown that compression of the material leads to reduction of the transmission loss of the barrier materials and absorption coefficient of absorbing materials. In this regard, “thickness reduction” and “variations of physical parameters” due to compression are investigated.

Utilization of Treated Red Meranti Wood Dust as Polymer Foam Composite for Acoustic Study

2013 ◽  
Vol 594-595 ◽  
pp. 760-764 ◽  
Author(s):  
Shafizah Sa'adon ◽  
Anika Zafiah M. Rus
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Wood Dust ◽  
Polymer Foam ◽  
Tube Test ◽  
Acoustic Study ◽  
Foam Composite ◽  
Absorbing Materials ◽  
Scanning Electron

A Red Meranti Wood Dust (RMD) act as a filler for polymer foam composite has been investigated and proved to have ability to absorb sound. In this study, treatment of wood dust with and without acid hydrolysis named as WDB and WDA respectively was use as filler. This study was developed to compare the ability of sound absorption based on treated filler and particle size of wood dust. By choosing the size of 355 μm, three different percentage has been selected which is 10%, 15% and 20% for both conditions. These samples has been tested by using Impedance Tube test according to ASTM E-1050 for sound absorption coefficient, α measurement and Scanning Electron Microscopy (SEM) for determine the porosity for each samples. 10% loaded of WDB as filler gives highest sound absorption coefficient of 0.999 at 4015.63 Hz. Meanwhile for 20% loaded of WDA gives 0.997 at 3228.13 Hz. When comparing the sound absorption coefficient for both sounds absorbing materials, WDB-polymer foam composite RMD showed higher value of sound absorption coefficient, α at higher frequency as compared to WDA-polymer foam composite.

scholarly journals Study on Auditory Perception Variability Caused by Distinct Structural Parameters of the Enclosure Space

2018 ◽  
Vol 36 (4) ◽  
pp. 671-678
Author(s):  
Rong Li ◽  
Xiangyang Zeng ◽  
Haitao Wang ◽  
Na Li
Keyword(s):  
Absorption Coefficient ◽  
Field Measurement ◽  
Auditory Perception ◽  
Structural Parameters ◽  
Measurement Techniques ◽  
Real Life ◽  
Sound Field ◽  
Scene Simulation ◽  
Auditory Scene ◽  
Acoustic Evaluation

The enclosure space is widespread in real life. However, from the angle on spatial hearing to study the variation of auditory perception caused by the changed structural parameters (such as volume, shape, etc) are very rare, particular in systematically research. In this paper, based on auditory scene simulation, the binaural auralization and sound field measurement techniques are used to obtain plenty of binaural signals in diverse enclosure spaces with different structural parameters. Subsequently, with the aid of the acoustic evaluation, the quantitative evaluation of spatial auditory perception change and its degree was carried out on the binaural signal. Major findings are summarized as follows:①The change of the volume, shape, absorption coefficient of indoor walls of enclosure space can induce the variation of auditory perception of sound field. According to the degree of change (from obvious to not), the absorption coefficient of indoor walls, the shape, the volume is sorted. ②changing the receiving location could affect the variation on auditory perception caused by the volume and shape of an enclosure space.

scholarly journals The influence of the distribution of sound absorbing materials on the estimation of reverberation time in rooms

2018 ◽  
Vol 49 ◽  
pp. 00078
Author(s):  
Marcelina Olechowska ◽  
Artur Nowoświat ◽  
Jan Ślusarek ◽  
Mateusz Latawiec
Keyword(s):  
Absorption Coefficient ◽  
Acoustic Field ◽  
Sound Absorption ◽  
Sound Field ◽  
Reverberation Time ◽  
Type D ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
Different Dimensions ◽  
Materials Used

Reverberation time in rooms depends on many factors, e.g. cubature, surface of envelopes, sound absorption coefficient of materials used for the construction of the envelopes, geometry of rooms or the distribution of sound absorbing materials. The arrangement of sound absorbing materials in rooms has an impact on the dispersion of acoustic field, yet theoretical calculation models do not take into account this impact. According to these models, regardless of the arrangement of sound absorbing materials, the reverberation time in a room will remain unchanged. The present paper investigates the above problem by means of computer simulations. For the needs of the simulation, three rooms with different dimensions were adopted, i.e. type 'p' - a cuboidal room with a square base, type 'd' - a cuboidal room (with one side of the 'p' room lengthened), type 'w' - a cuboidal room (with the height of the room lengthened 'p'). During the simulation, the way of acoustic field dispersion was being changed and its influence on the reverberation time in the rooms was being determined. The authors investigated two situations. The first one involved a non-dampened room, in which the sound absorbing material was being arranged differently. The second one involved a welldampened room, and the dispersion of sound field was analyzed depending on the location of the reflecting material.

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