A numerical study of a method for measuring the effective <i>in situ</i> sound absorption coefficient

Kuipers, E.R.; Wijnant, Ysbrand H.; Boer, A. de

doi:10.1121/1.4745839

Cited by 7 publications

(9 citation statements)

References 11 publications

(22 reference statements)

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“…Figure 14 shows the area-averaged effective sound absorption coefficient for three different sizes of S p .T his graph clearly illustrates that al arger surface leads to less variations in the sound absorption curve. The same behavior waso bserved in [23]. The explanation for this effect is that interferences (room reflections, diffracted waves) are averaged out more strongly as the surface area increases.…”

Section: Microphone (8x) Spacersupporting

confidence: 48%

“…Schematic top viewof3Dintensity probe in front of aplanar surface. Figure 12 shows the area-averaged sound absorption coefficient, determined using equations (21) and (23).Ifthe flowofactive acoustic power through the circumferential area is not accounted for,the solid gray curveisobtained. This curvematches the theoretical, dashed gray,curvefor d = 0.02 mtaken from Figure 6quite well.…”

Section: Microphone (8x) Spacermentioning

confidence: 99%

“…Previously [23], numerical investigations were performed to investigate the accuracyo ft he LPW-method. It was found that the accuracyincreases with decreasing distance of the measurement surface to the material surface.…”

Section: Analysis Of the Sound Field In Front Of An Acoustically Hardmentioning

confidence: 99%

“…Numerical investigations [23] showed that, accurate estimates for the normal incidence sound absorption coefficient can be obtained, even in the presence of interfering reflections. Hence, area-averaging seems effective in reducing the effects caused by such reflections.…”

Section: Introductionmentioning

confidence: 99%

“…This novelmeasurement method employs aL ocal Plane Wave Assumption, and is therefore called the LPW-method. It yields the exact sound absorption coefficient for plane wavest hat are normally incident upon alocally-reacting surface, butalso yields accurate results for near-normal incidence, even if additional reflections are present [20,21,22,23]. By using the LPW-method, at asmall distance from the surface of interest, one can straightforwardly determine the local, ©S.Hirzel Verlag · EAA Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Measuring Sound Absorption: Considerations on the Measurement of the Active Acoustic Power

Kuipers¹,

Wijnant²,

Boer³

2014

Acta Acustica united with Acustica

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SummaryUsing alocal plane wave assumption, one can determine the normal incidence sound absorption coefficient of a surface by measuring the acoustic pressure and the particle velocity normal to that surface. As the measurement surface lies in front of the material surface, the measured active and incident acoustic power will generally deviate from those at the material surface, leading to ap ossibly inaccurate sound absorption coefficient. This phenomenon is particularly pronounced for poorly absorbing surfaces if sound is not normally incident overthe whole material surface. Based on an analytical model, it is shown that the accuracycan be improvedbyextending the measurement surface upon which the active acoustic power is measured. Experimental results demonstrate the usefulness of this approach, in particular for poorly absorbing surfaces.

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Section: Microphone (8x) Spacersupporting

confidence: 48%

Section: Microphone (8x) Spacermentioning

confidence: 99%

Section: Analysis Of the Sound Field In Front Of An Acoustically Hardmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Measuring Sound Absorption: Considerations on the Measurement of the Active Acoustic Power

Kuipers¹,

Wijnant²,

Boer³

2014

Acta Acustica united with Acustica

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Inexpensive indoor acoustic material estimation for realistic sound propagation

Kim

Yoon

2022

Computer Animation & Virtual

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For the realistic and immersive experience in a virtual environment, it is important to estimate and reflect the acoustic characteristic of the real indoor scenes. This article proposes a method of directly measuring the reflection coefficient of a surface, which is an acoustic characteristics in the real environment. Because expensive optimization‐based studies that mainly aim to reproduce recorded sounds indirectly estimate acoustic materials, new estimates are required whenever the actual environment changes. Our approach utilizes the method of the acoustics field to enable anyone to easily and directly measure the reflection coefficient of a real environment and generate sound in a virtual environment. We obtain the impulse response (IR) for the target surface, separate the direct sound and the reflected sound, and calculate the reflection coefficient for each surface. The measurement of the IR and the reflection coefficient calculation takes about 2 s. Our result produces a sound with a similar reverberation time to the sound recorded in the real environment.

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On the area-averaged effective sound absorption coefficient of porous materials excited by a monopole

Sgard,

Atalla,

Robin

et al. 2024

The Journal of the Acoustical Society of America

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The area-averaged effective sound absorption coefficient (SAC) of a rigid-backed homogeneous porous material subjected to a monopole excitation is calculated as the absorbed-to-incident sound power ratio. Using Allard's model to describe the sound propagation above the porous material, an analytical model for this power-based SAC is proposed and proves to give a good approximation of the sound absorption performance under monopole excitation of sufficiently large areas of material. The impact of factors on the power-based SAC, such as monopole height, material radial dimension used to calculate the sound powers, and material properties is discussed. The power-based SAC frequency-dependent behavior is analyzed through sound intensity field assessments at the material surface and is compared to normal incident plane wave and diffuse field SACs. The sound absorption behavior of sound absorbers under monopole excitation exhibits notable distinctions and peculiar results compared to those observed under plane wave and diffuse fields, particularly at low frequencies and for sources close to the material.

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A numerical study of a method for measuring the effective in situ sound absorption coefficient

Cited by 7 publications

References 11 publications

Measuring Sound Absorption: Considerations on the Measurement of the Active Acoustic Power

Measuring Sound Absorption: Considerations on the Measurement of the Active Acoustic Power

Inexpensive indoor acoustic material estimation for realistic sound propagation

On the area-averaged effective sound absorption coefficient of porous materials excited by a monopole

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