Availability of Reference Sound Sources for Qualification of Hemi-Anechoic Rooms Based on Deviation of Sound Pressure Level from Inverse Square Law

Keisuke YAMADA; Hironobu TAKAHASHI; Ryuzo HORIUCHI

doi:10.1587/transfun.E101.A.211

Availability of Reference Sound Sources for Qualification of Hemi-Anechoic Rooms Based on Deviation of Sound Pressure Level from Inverse Square Law

Keisuke YAMADA, Hironobu TAKAHASHI, Ryuzo HORIUCHI

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The sound power level is a physical quantity indispensable for evaluating the amount of sound energy radiated from electrical and mechanical apparatuses. The precise determination of the sound power level requires the qualification of the measurement environment, such as a hemi-anechoic room, by estimating the deviation of the sound pressure level from the inverse-square law. In this respect, Annex A of ISO 3745 specifies the procedure for room qualification and defines a tolerance limit for the directivity of the sound source, which is used for the qualification. However, it is impractical to prepare a special loudspeaker only for room qualification. Thus, we developed a simulation method to investigate the influence of the sound source directivity on the measured deviation of the sound pressure level from the inverse-square law by introducing a quantitative index for the influence of the directivity. In this study, type 4202 reference sound source by Brüel & Kjær was used as a directional sound source because it has been widely used as a reference standard for the measurement of sound power levels. We experimentally obtained the directivity of the sound source by measuring the sound pressure level over the measurement surface. Moreover, the proposed method was applied to the qualification of several hemi-anechoic rooms, and we discussed the availability of a directional sound source for the process. Analytical results showed that available reference sound sources may be used for the evaluation of hemi-anechoic rooms depending on the sound energy absorption coefficient of the inner wall, the directionality of the microphone traverse, and the size of the space to be qualified. In other words, the results revealed that a reference sound source that is once quantified by the proposed method can be used for qualifying hemi-anechoic rooms.

Publication: IEICE TRANSACTIONS on Fundamentals Vol.E101-A No.1 pp.211-218

Publication Date: 2018/01/01

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Online ISSN: 1745-1337

DOI: 10.1587/transfun.E101.A.211

Type of Manuscript: PAPER

Category: Engineering Acoustics

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Keisuke YAMADA, Hironobu TAKAHASHI, Ryuzo HORIUCHI, "Availability of Reference Sound Sources for Qualification of Hemi-Anechoic Rooms Based on Deviation of Sound Pressure Level from Inverse Square Law" in IEICE TRANSACTIONS on Fundamentals, vol. E101-A, no. 1, pp. 211-218, January 2018, doi: 10.1587/transfun.E101.A.211.
Abstract: The sound power level is a physical quantity indispensable for evaluating the amount of sound energy radiated from electrical and mechanical apparatuses. The precise determination of the sound power level requires the qualification of the measurement environment, such as a hemi-anechoic room, by estimating the deviation of the sound pressure level from the inverse-square law. In this respect, Annex A of ISO 3745 specifies the procedure for room qualification and defines a tolerance limit for the directivity of the sound source, which is used for the qualification. However, it is impractical to prepare a special loudspeaker only for room qualification. Thus, we developed a simulation method to investigate the influence of the sound source directivity on the measured deviation of the sound pressure level from the inverse-square law by introducing a quantitative index for the influence of the directivity. In this study, type 4202 reference sound source by Brüel & Kjær was used as a directional sound source because it has been widely used as a reference standard for the measurement of sound power levels. We experimentally obtained the directivity of the sound source by measuring the sound pressure level over the measurement surface. Moreover, the proposed method was applied to the qualification of several hemi-anechoic rooms, and we discussed the availability of a directional sound source for the process. Analytical results showed that available reference sound sources may be used for the evaluation of hemi-anechoic rooms depending on the sound energy absorption coefficient of the inner wall, the directionality of the microphone traverse, and the size of the space to be qualified. In other words, the results revealed that a reference sound source that is once quantified by the proposed method can be used for qualifying hemi-anechoic rooms.
URL: https://globals.ieice.org/en_transactions/fundamentals/10.1587/transfun.E101.A.211/_p

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@ARTICLE{e101-a_1_211,
author={Keisuke YAMADA, Hironobu TAKAHASHI, Ryuzo HORIUCHI, },
journal={IEICE TRANSACTIONS on Fundamentals},
title={Availability of Reference Sound Sources for Qualification of Hemi-Anechoic Rooms Based on Deviation of Sound Pressure Level from Inverse Square Law},
year={2018},
volume={E101-A},
number={1},
pages={211-218},
abstract={The sound power level is a physical quantity indispensable for evaluating the amount of sound energy radiated from electrical and mechanical apparatuses. The precise determination of the sound power level requires the qualification of the measurement environment, such as a hemi-anechoic room, by estimating the deviation of the sound pressure level from the inverse-square law. In this respect, Annex A of ISO 3745 specifies the procedure for room qualification and defines a tolerance limit for the directivity of the sound source, which is used for the qualification. However, it is impractical to prepare a special loudspeaker only for room qualification. Thus, we developed a simulation method to investigate the influence of the sound source directivity on the measured deviation of the sound pressure level from the inverse-square law by introducing a quantitative index for the influence of the directivity. In this study, type 4202 reference sound source by Brüel & Kjær was used as a directional sound source because it has been widely used as a reference standard for the measurement of sound power levels. We experimentally obtained the directivity of the sound source by measuring the sound pressure level over the measurement surface. Moreover, the proposed method was applied to the qualification of several hemi-anechoic rooms, and we discussed the availability of a directional sound source for the process. Analytical results showed that available reference sound sources may be used for the evaluation of hemi-anechoic rooms depending on the sound energy absorption coefficient of the inner wall, the directionality of the microphone traverse, and the size of the space to be qualified. In other words, the results revealed that a reference sound source that is once quantified by the proposed method can be used for qualifying hemi-anechoic rooms.},
keywords={},
doi={10.1587/transfun.E101.A.211},
ISSN={1745-1337},
month={January},}

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TY - JOUR
TI - Availability of Reference Sound Sources for Qualification of Hemi-Anechoic Rooms Based on Deviation of Sound Pressure Level from Inverse Square Law
T2 - IEICE TRANSACTIONS on Fundamentals
SP - 211
EP - 218
AU - Keisuke YAMADA
AU - Hironobu TAKAHASHI
AU - Ryuzo HORIUCHI
PY - 2018
DO - 10.1587/transfun.E101.A.211
JO - IEICE TRANSACTIONS on Fundamentals
SN - 1745-1337
VL - E101-A
IS - 1
JA - IEICE TRANSACTIONS on Fundamentals
Y1 - January 2018
AB - The sound power level is a physical quantity indispensable for evaluating the amount of sound energy radiated from electrical and mechanical apparatuses. The precise determination of the sound power level requires the qualification of the measurement environment, such as a hemi-anechoic room, by estimating the deviation of the sound pressure level from the inverse-square law. In this respect, Annex A of ISO 3745 specifies the procedure for room qualification and defines a tolerance limit for the directivity of the sound source, which is used for the qualification. However, it is impractical to prepare a special loudspeaker only for room qualification. Thus, we developed a simulation method to investigate the influence of the sound source directivity on the measured deviation of the sound pressure level from the inverse-square law by introducing a quantitative index for the influence of the directivity. In this study, type 4202 reference sound source by Brüel & Kjær was used as a directional sound source because it has been widely used as a reference standard for the measurement of sound power levels. We experimentally obtained the directivity of the sound source by measuring the sound pressure level over the measurement surface. Moreover, the proposed method was applied to the qualification of several hemi-anechoic rooms, and we discussed the availability of a directional sound source for the process. Analytical results showed that available reference sound sources may be used for the evaluation of hemi-anechoic rooms depending on the sound energy absorption coefficient of the inner wall, the directionality of the microphone traverse, and the size of the space to be qualified. In other words, the results revealed that a reference sound source that is once quantified by the proposed method can be used for qualifying hemi-anechoic rooms.
ER -