## A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions

Publication: Research - peer-review › Journal article – Annual report year: 2009

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**A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions.** / Jeong, Cheol-Ho.

Publication: Research - peer-review › Journal article – Annual report year: 2009

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*Journal of the Acoustical Society of America*, vol 125, no. 4, pp. 2064-2071. DOI: 10.1121/1.3081392

### APA

*Journal of the Acoustical Society of America*,

*125*(4), 2064-2071. DOI: 10.1121/1.3081392

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*Journal of the Acoustical Society of America*. 2009, 125(4). 2064-2071. Available: 10.1121/1.3081392

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TY - JOUR

T1 - A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions

AU - Jeong,Cheol-Ho

N1 - Copyright (2009) Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.

PY - 2009

Y1 - 2009

N2 - Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between the theoretical absorption coefficient and the reverberation room measurement. The angle-weighted absorption coefficient, together with the size correction, agrees satisfactorily with the measured absorption data by the reverberation chamber method. At high frequencies and for large samples, the averaged weighting corresponds well with the measurement, whereas at low frequencies and for small panels, the relatively flat distribution agrees better.

AB - Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between the theoretical absorption coefficient and the reverberation room measurement. The angle-weighted absorption coefficient, together with the size correction, agrees satisfactorily with the measured absorption data by the reverberation chamber method. At high frequencies and for large samples, the averaged weighting corresponds well with the measurement, whereas at low frequencies and for small panels, the relatively flat distribution agrees better.

U2 - 10.1121/1.3081392

DO - 10.1121/1.3081392

M3 - Journal article

VL - 125

SP - 2064

EP - 2071

JO - Acoustical Society of America. Journal

T2 - Acoustical Society of America. Journal

JF - Acoustical Society of America. Journal

SN - 0001-4966

IS - 4

ER -