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ANSI/ASA S12.55-2012 / ISO 3745:2012 (R2019)American National Standard Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for anechoic and hemi-anechoic rooms (a nationally adopted international stand >
ANSI/ASA S12.55-2012 / ISO 3745:2012 (R2019)American National Standard Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for anechoic and hemi-anechoic rooms (a nationally adopted international stand, 2012
- 1 Scope
- 1.1 General
- 1.2 Types of noise and noise sources
- 1.3 Test room
- 1.4 Measurement uncertainty
- 2 Normative references
- 3 Terms and definitions
- 4 Reference meteorological conditions
- 5 Test rooms
- 5.1 Acoustic criterion for adequacy of the test room
- 5.2 Criteria for background noise
- 5.3 Criterion for air temperature
- 6 Instrumentation
- 6.1 Instruments for acoustical measurements
- 6.2 Instruments for meteorological measurements
- 7 Definition, location, installation and operation of noise source under test
- 7.1 General
- 7.2 Auxiliary equipment
- 7.3 Noise source location
- 7.4 Mounting of the noise source
- 7.5 Operation of source during test
- 8 Measurement surface
- 8.1 Spherical measurement surface for use in an anechoic room
- 8.2 Hemispherical measurement surface for use in a hemi-anechoic room
- 9 Determination of sound power levels and sound energy levels
- 9.1 Measurements in the test room
- 9.2 Measurement of meteorological conditions
- 9.3 Microphone positions
- 9.4 Determination of sound power levels of a noise source which emits steady or non-steady noise19 9.5 Determination of sound energy levels for a noise source which emits impulsive noise
- 9.6 Calculation of directivity indices
- 9.7 Calculation of surface sound pressure level non-uniformity index
- 9.8 Frequency-weighted sound power level and sound energy level
- 10 Measurement uncertainty
- 10.1 Methodology
- 10.2 Determination of .omc
- 10.3 Determination of .R0
- 10.4 Typical upper bound values of .R0
- 10.5 Total standard deviation, .tot, and expanded measurement uncertainty, U
- 11 Information to be recorded
- 11.1 General
- ii © 2012 Acoustical Society of America—All rights reserved. 11.2 Noise source under test
- 11.3 Test room
- 11.4 Instrumentation
- 11.5 Acoustical data
- 12 Test report
- Annex A (normative) General procedures for qualification of anechoic and hemi-anechoic rooms
- A.1 General
- A.2 Instrumentation and measuring equipment
- A.3 Installation of test sources and microphones
- A.4 Test procedures
- A.5 Qualification procedure
- Annex B (normative) Qualification procedure for spaces within test rooms used in the determination of sound power levels and sound energy levels of specific noise sources
- B.1 General
- B.2 Properties of reflecting plane
- B.3 Procedure using two measurement spheres or hemispheres with different radii (two-surface method
- Annex C (normative) Calculation of A-weighted sound power levels and A-weighted sound energy levels from one-third-octave band levels
- C.1 A-weighted sound power levels
- C.2 A-weighted sound energy levels
- C.3 Values of j and Cj for use in calculations
- Annex D (normative) Array of microphone positions on a spherical measurement surface in a free field
- Annex E (normative) Arrays of microphone positions on a hemispherical measurement surface in a hemi-free field
- Annex F (normative) Coaxial circular paths of microphones on a hemispherical measurement surface in a hemi-free field
- Annex G (normative) Meridional paths of microphones on a hemispherical measurement surface in a hemi-free field
- Annex H (normative) Spiral paths of microphones on a hemispherical measurement surface in a hemifree field
- Annex I (informative) Guidance on the development of information on measurement uncertainty
- I.1 General
- I.2 Considerations on the total standard deviation, .tot
- I.3 Considerations on .omc
- I.4 Considerations on .R0
- I.5 Combined standard uncertainty
- I.6 Measurement uncertainty based on reproducibility data
- I.7 Example of an uncertainty budget for a reference sound source in a national laboratory [Go to Page]