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Sound Absorption Measurement |
Laboratory Measurement
Complied with:
- ASTM C423-02
- ASTM E795-93
@
SCUT Branch Laboratory
(South China University of Technology,
Guangzhou, China)
Complied with:
- ASTM C423-02
- ASTM E795-93
- ISO 354:2003
- EN ISO 11654:1997
- BS EN 1793-1:1998 and BS EN 1793-3:1998
Field Measurement
Complied with:
- ASTM C423-02
- Annex X2 of ASTM C423-02
The Sound absorption
measurement was carried out according to ASTM C-423 'Standard Test Method
for Sound Absorption and Sound Absorption Coefficients by the Reverberation
Room Method'. A band of random noise is used as a test signal and turned
on long enough for the sound pressure level in the room to reach a steady
state. When the signal is turn off, the sound pressure level will decrease
average within determined from measurements of the average time for the
sound pressure level in order to get the decay rate, which is a specified
frequency band to decay through a certain range.
The absorption of the reverberation room is measured as both before and after placing a specimen of sound absorptive material in the room. The minimum number of decay measurements required for each frequency band is six. At least one loudspeaker position and three microphone positions with two readings in each case shall be used.
The absorption coefficient, of the room surface covered by the specimen should be added when it is significant. However, the absorption coefficients of a smooth, hard, rigid surface, such a reverberation room floor, are small that they may be neglected. It is required that no adjustment be made for the floor area covered by the specimen.
A single number rating called the Noise Reduction Coefficient (NRC). Round the average of the sound absorption coefficient calculated in 250 Hz, 500 Hz, 1000 Hz and 2000 Hz to the nearest multiple of 0.05. If the unrounded average is an exact midpoint, round to the next higher multiple of 0.05.
Reverberation Chamber
in City University of Hong Kong
The reverberation chamber was joint established by (A+A)*L
and the Department of Building and Construction, City University of Hong
Kong, in the summer of 2001. It is used for teaching, research, and commercial
consultancy in architectural acoustics.
This reverberation chamber meets all requirements of ISO 354: 1985 and
ASTM C423-99a. It is mainly made of massive concrete and damped steel.
The reverberant sound field within the chamber is closely diffuse during
the steady and decay states.
(A+A)*L CityU
Dimension 
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| Open ceremony of Reverberation Chamber in CityU | Prof. Po S. Chung, Dr. Westwood Hong & Prof. Andrew Y T Leung in the open ceremony |
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Laboratory Measurement Setup at CityU |
Laboratory Measurement for Lightweight Concrete |
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Measurement for False Ceiling |
Measurement for Concrete Absorber |
Reverberation Chamber in South China University
of Technology, Guangzhou, China
The reverberation chamber was established by the College of Architecture
& Civil Engineering South China University of Technology, Guangzhou,
China. All the laboratory measurement and quality control system was under
supervision and performed by Acoustics and Air Testing Laboratory Company
Limited - (A+A)*L.
This reverberation chamber meets all requirements of ISO 354: 1985 and
ASTM C423-02.
(A+A)*L SCUT Dimension
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Laboratory in SCUT |
Laboratory Setup at SCUT |
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Laboratory Measurement Setup at SCUT |
Field Reverberation Measurement
Absorption material, like false ceiling and acoustic panel, is an essential component in big capacity room to ensure a good acoustics environment. A good design room should provide a suitable reverberation time for people listen and communicate without disturbing. The reverberation time is a good indicator for the effectiveness of absorption material.
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Field Measurement Setup |
Field Measurement in Classroom |
Job Reference
1. Goldtech Building Material Co .Ltd.
(1996)
Laboratory Absorption Measurement for the Acoustic Plaster according to
ASTM C 423.
2. Erawan Co. Ltd. (1996)
Laboratory Absorption Measurement for the Acoustic Plaster according to
ASTM C 423.
3. Pyrok Industries Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Plaster for West Rail Project
CC203 according to ASTM C 423.
4. Dominic Science & Technology Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Plaster according to ASTM
C 423.
5. Campbell & Shillinglaw Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Panel according to ASTM
C 423.
6. Tai Ming Fung Co. Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Plaster according to ASTM
C 423.
7. Cemac Engineering Co. Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Wall Lining according to
ASTM C 423
8. Kim & Kris Enterprises (Far East) Ltd. (2000)
Laboratory Absorption Measurement for Acoustic Ceiling System according
to ASTM C 423.
9. Campbell & Shillinglaw, Lau Ltd. (2001)
Laboratory Absorption Measurement for Metal Roof System according to ASTM
C 423 for CLP Power Hong Kong Limited Science Park Project.
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10. S. M. Engineering Ltd. (2001)
Laboratory Absorption Measurement for Metal Roof System according to ASTM
C 423 for CLP Power Hong Kong Limited West Kowloon Reclamation 'A' Substation
and Maintenance Depot.
11. Cemac Engineering Co. Ltd. (2001)
Laboratory Absorption Measurement for Acoustic Wall Lining according to
ASTM C 423
12. Eastwell Enterprise (Asia) Co. Ltd. (2001)
Normal Incidence Sound Absorption Coefficient Measurement according to
ASTM 1050 "Standard test Method for Impedance and Absorption of Acoustical
Materials Using A tube, Two Microphones and A Digital frequency Analysis
System" for four different WFC testing samples