Experimental study of wood acoustic absorption characteristics

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 467-476 ◽  
Author(s):  
Jerzy Smardzewski ◽  
Wojciech Batko ◽  
Tadeusz Kamisiński ◽  
Artur Flach ◽  
Artur Pilch ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Laboratory Measurements ◽  
Absorption Coefficients ◽  
Tropical Zone ◽  
Fiber Dimensions ◽  
Air Flow Resistivity ◽  
Oak Ash

Abstract The objective of this study was to determine normal impedance on the surface as well as sound absorption coefficients for several wood species from Europe and from the tropical zone. The mathematical models of Miki, Attenborough, and Allard – dealing with acoustic properties of porous materials – have also been compared. The air flow resistivity exhibits a distinct link between fiber dimensions and wood porosity. The highest sound absorption coefficient was found for oak, ash, sapeli, and pine woods at 2 kHz frequency. The Attenborough model provides results closest to laboratory measurements, although it still requires significant improvements. The Miki and Allard models have some drawbacks and should be applied with reservation for the determination of wood acoustic properties.

scholarly journals The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shuming Chen ◽  
Yang Jiang ◽  
Jing Chen ◽  
Dengfeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Polyurethane Foams ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Absorption Properties ◽  
Maximum Enhancement ◽  
Flexible Polyurethane ◽  
Pu Foams

Flexible polyurethane (PU) foams comprising various additive components were synthesized to improve their acoustic performances. The purpose of this study was to investigate the effects of various additive components of the PU foams on the resultant sound absorption, which was characterized by the impedance tube technique to obtain the incident sound absorption coefficient and transmission loss. The maximum enhancement in the acoustic properties of the foams was obtained by adding fluorine-dichloroethane (141b) and triethanolamine. The results showed that the acoustic absorption properties of the PU foams were improved by adding 141b and triethanolamine and depended on the amount of the water, 141b, and triethanolamine.

scholarly journals The Use of Fabrics to Improve the Acoustic Absorption: Influence of the Woven Fabric Thread Density Over a Nonwoven

2018 ◽  
Vol 18 (3) ◽  
pp. 269-280 ◽  
Author(s):  
Pilar Segura-Alcaraz ◽  
Jorge Segura-Alcaraz ◽  
Ignacio Montava ◽  
Marilés Bonet-Aracil
Keyword(s):  
Sound Absorption ◽  
Woven Fabric ◽  
Acoustic Absorption ◽  
Human Beings ◽  
Absorption Coefficients ◽  
Acoustic Characteristics ◽  
Resistive Layer ◽  
Acoustic Absorption Coefficient ◽  
Impedance Tube Method

Abstract Noise is frequently unnoticed, but it is one of the causes of unhealth for human beings reducing people’s quality of life. There are many materials that can be considered as acoustic absorbents. Textiles can be used to both improve the acoustic quality of and to decorate the room where they have been placed. In this study, we used some fabrics with 15, 20 and 30 ends/cm and 15, 20 and 30 picks/cm. The acoustic absorption coefficient was measured when the fabric was added as a resistive layer on top of a nonwoven made of polyester fiber. Results evidence that these fabrics can be efficiently used to modify the acoustic absorption of the nonwoven. Sound absorption coefficients measured via the impedance tube method show that these modifications occur. The results show how it is possible to improve the acoustic characteristics of a simple nonwoven to obtain sound absorption coefficients close to values of 1 at different frequencies by choosing a fabric with the appropriate combination of warp and weft count.

Assessment of the Acoustic Properties in Octavo Bands for Selected Polyurethane Materials

2016 ◽  
Vol 246 ◽  
pp. 7-10
Author(s):  
Tomasz Małysa ◽  
Krzysztof Nowacki ◽  
Teresa Lis
Keyword(s):  
Polyurethane Foam ◽  
Sound Absorption ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Impedance Tube

The article presents the acoustic properties of selected polyurethane materials. The study involved a porous polyurethane foam primary and secondary, for whom assigned the value of sound absorption coefficients in the frequency range of 100 – 1250 Hz. The study was conducted in impedance tube Kundt.

scholarly journals On the Determination of Acoustic Properties of Membrane Type Structural Skin Elements by Means of Surface Displacements

2021 ◽  
Vol 11 (21) ◽  
pp. 10357
Author(s):  
Daniel Urbán ◽  
N. B. Roozen ◽  
Vojtech Jandák ◽  
Marek Brothánek ◽  
Ondřej Jiříček
Keyword(s):  
Plane Wave ◽  
Sound Absorption ◽  
Sound Pressure ◽  
Transmission Loss ◽  
Laser Doppler Vibrometer ◽  
Sound Transmission ◽  
Acoustic Properties ◽  
Sound Transmission Loss ◽  
Membrane Type

The article focuses on the determination of the acoustic properties (sound transmission loss, sound absorption and transmission coefficient under acoustic plane wave excitation) of membrane-type of specimens by means of a combination of incident plane wave sound pressure and membrane surface displacement information, measuring the sound pressure with a microphone and the membrane displacement by means of a laser Doppler vibrometer. An overview of known measurement methods and the theoretical background of the proposed so-called mobility-based method (MM) is presented. The proposed method was compared with the conventional methods for sound transmission loss and absorption measurement in the impedance tube, both numerically and experimentally. Finite element model (FEM) simulation results of two single layer membrane samples of different shape configurations were compared, amongst which six different variations of the backing wall termination. Four different approaches to determine the sound transmission loss and two methods to determine sound absorption properties of the membranes were compared. Subsequently, the proposed method was tested in a laboratory environment. The proposed MM method can be possibly used to measure the vibro-acoustic properties of building parts in situ.

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