Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

Doutres, Olivier; Salissou, Yacoubou; Atalla, Noureddine; Panneton, Raymond

doi:10.1016/j.apacoust.2010.01.007

Cited by 138 publications

(96 citation statements)

References 14 publications

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“…In this situation, the experimentally measured effective density and effective bulk modulus could be used to quantify a 1 , K, K 0 , and k 0 0 from analytical inversion, 25,26 if one directly measures the porosity / and the permeability k 0 . 27 As rigid-frame behavior cannot be completely assumed here (see Fig. 5 and Appendix C), we used direct measurements of the permeability and the sound absorption of the fibrous material under study to validate this reconstruction approach.…”

Section: Resultsmentioning

confidence: 99%

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Luu

Perrot

Monchiet

et al. 2017

The Journal of the Acoustical Society of America

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The main purpose of this article is to present, within a unified framework, a technique based on numerical homogenization, to model the acoustical properties of real fibrous media from their geometrical characteristics and to compare numerical results with experimental data. The authors introduce a reconstruction procedure for a random fibrous medium and use it as a basis for the computation of its geometrical, transport, and sound absorbing properties. The previously ad hoc “fiber anisotropies” and “volume weighted average radii,” used to describe the experimental data on microstructure, are here measured using scanning electron microscopy. The authors show that these parameters, in conjunction with the bulk porosity, contribute to a precise description of the acoustical characteristics of fibrous absorbents. They also lead to an accurate prediction of transport parameters which can be used to predict acoustical properties. The computed values of the permeability and frequency-dependent sound absorption coefficient are successfully compared with permeability and impedance-tube measurements. The authors' results indicate the important effect of fiber orientation on flow properties associated with the different physical properties of fibrous materials. A direct link is provided between three-dimensional microstructure and the sound absorbing properties of non-woven fibrous materials, without the need for any empirical formulae or fitting parameters.

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Section: Resultsmentioning

confidence: 99%

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Luu

Perrot

Monchiet

et al. 2017

The Journal of the Acoustical Society of America

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“…An alternative laboratory method to measure more fundamental acoustical properties of porous media is to use the three-microphone impedance tube as suggested originally by Iwase 15 and subsequently revisited by Doutres, et al 16 Figure 2 illustrates the basic setup that can be used to measure directly the characteristic impedance and complex wavenumber. These properties can be used to estimate the dynamic density and complex compressibility from the following equations:…”

Section: Methods For Parameter Inversion Based On Asymptotic Behaviourmentioning

confidence: 99%

“…A 3-microphone impedance tube setup to measure the surface impedance of a porous layer. 16 where c 0 is the sound speed in fluid. The reproducibility of this method is discussed in ref., 12 where it was shown that the variation in the measured acoustical properties can be considerable if the material is not homogeneous.…”

Section: Methods For Parameter Inversion Based On Asymptotic Behaviourmentioning

confidence: 99%

A Review of Acoustical Methods for Porous Material Characterisation

Horoshenkov¹

2017

IJAV

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The purpose of this paper is to present and discuss a range of in-situ and laboratory methods can be used to measure the morphological characteristics of porous materials. In the case of foams and granular media used for noise control applications, the most common of these characteristics are pore size and its distribution, porosity, and pore connectivity. In the case of fibrous media, the most useful non-acoustical characteristics are the fibre size and packing density. In the case of outdoor surfaces such as gravel, sandy soils, and agricultural land, which can be partly saturated with water, it is of direct interest to measure the degree of water saturation hydraulic permeability and pore size gradient. In the case of materials with good physiochemical properties, it is of interest to determine their internal pore surface area, porosity, and pore size scales. In this paper, the existing and newly emerging acoustic characterisation methods are discussed in terms of their complexity, accuracy, and sample requirements. The application of these methods relate to traditional needs to measure and predict the in-situ performance of noise control elements and outdoor surfaces, to ensure the quality control during material manufacturing process and to be able to measure non-invasively the micro-and nano-structure of porous media which is used in catalytic filters, electric capacitors and for gas storage. Parts of this paper were presented at the 22nd International Congress on Sound and Vibration in Florence.

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“…24 The indirect method associated to the 3-microphone impedance tube method has been recently detailed by the authors in Ref. 25. The tube used for the measurements has a 44.5 mm inner diameter and the loudspeaker at one end generates a broadband random signal in the frequency band 200À4100 Hz.…”

Section: -3mentioning

confidence: 99%

“…The anisotropy threshold is set here to DA ¼ 1. 25 and it is found that 15 materials on 17 can be considered as isotropic ( we are interested in linking cell microstructure to nonacoustic parameters from simple models, only the 15 materials having isotropic cells are considered in the analysis. For each material, mean strut length l [lm] and thickness t [lm] are also measured.…”

Section: A Microstructurementioning

confidence: 99%

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

Doutres¹,

Atalla²,

Dong³

2011

Journal of Applied Physics

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134

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The present paper proposes to investigate the links between the microstructure of polyurethane foams and their sound absorbing efficiency, and more specifically the effect of membranes closing the cells. This study is based on the complete characterization of 15 polyurethane foam with various cell sizes and reticulation rates (i.e., open pore content): (i) characterization of the microstructure properties (cell size C s , strut thickness t, reticulation rate R w …) from SEM pictures, (ii) characterization of nonacoustic parameters (porosity U, airflow resistivity r, tortuosity a 1 …) from direct and indirect methods. Existing analytical links between microstructure properties and nonacoustic parameters are first applied to fully reticulated materials. Then, they are improved empirically to account for the presence of the closed pore content. The proposed expressions associated to the Johnson-Champoux-Allard porous model allow a good estimation of the sound absorbing behavior of all polyurethane foams, fully reticulated or not. This paper also demonstrates the important effect of the presence of cell membranes: increase of the airflow resistivity, tortuosity, and the ratio between the thermal and viscous characteristic lengths while decreasing these two characteristic lengths. Thus, the sound absorption efficiency at low frequencies is improved but can be worsened in some higher frequency bands.

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Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

Cited by 138 publications

References 14 publications

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

A Review of Acoustical Methods for Porous Material Characterisation

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

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