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AS 5336:2019
$242.18
Acoustics – Determination of sound power levels and sound energy levels of noise sources using sound pressure – Precision methods for anechoic rooms and hemi – anechoic rooms
The objective of this Standard is to specify methods for measuring the sound pressure levels on a measurement surface enveloping a noise source (machinery and equipment) in an anechoic room or a hemi-anechoic room, in order to determine the sound power level or sound energy level produced by the noise source.
Table of contents
Header
About this publication
Preface
Foreword
Introduction
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
5.2.1 Relative criteria
5.2.1.1 General
5.2.1.2 Frequency band measurements
5.2.1.3 A-weighted measurements
5.2.2 Absolute criteria
5.2.3 Statement of non-conformity with criteria
5.3 Criterion for air temperature
6 Instrumentation
6.1 Instruments for acoustical measurements
6.1.1 General
6.1.2 Calibration
6.1.3 Verification
6.2 Instruments for meteorological measurements
6.2.1 General
6.2.2 Verification
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
7.4.1 General
7.4.2 Hand-held machinery and equipment
7.4.3 Base-mounted, wall-mounted and table-top machinery and equipment
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
9.3.1 General
9.3.2 Fixed positions for measurements on a spherical measurement surface in an anechoic room
9.3.3 Fixed positions for measurements on a hemispherical measurement surface in a hemi-anechoic room
9.3.4 Coaxial circular paths in parallel planes on a sphere or hemisphere (for measurements in a hemi-anechoic room)
9.3.5 Meridional arc traverses on a sphere or hemisphere
9.3.6 Spiral path on a sphere or hemisphere
9.3.7 Other microphone arrangements
9.4 Determination of sound power levels of a noise source which emits steady or non-steady noise
9.4.1 Measurement of sound pressure levels
9.4.2 Corrections for background noise
9.4.3 Calculation of surface time-averaged sound pressure levels
9.4.3.1 Measurement surface with segments having equal areas
9.4.3.2 Measurement surface with segments having unequal areas
9.4.3.3 Surface time-averaged sound pressure levels from measurements using meridional arc traverses or a spiral path
9.4.4 Calculation of sound power levels
9.4.4.1 Sound power level in an anechoic room
9.4.4.2 Sound power level in a hemi-anechoic room
9.4.4.3 Sound power level under different meteorological conditions
9.5 Determination of sound energy levels for a noise source which emits impulsive noise
9.5.1 Measurement of single event time-integrated sound pressure levels
9.5.2 Calculation of surface single event time-integrated sound pressure levels
9.5.3 Calculation of sound energy levels
9.5.3.1 Sound energy level in an anechoic room
9.5.3.2 Sound energy level in a hemi-anechoic room
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 σomc
10.3 Determination of σR0
10.3.1 General
10.3.2 Round robin test
10.3.3 Modelling approach for σR0
10.4 Typical upper bound values of σR0
10.5 Total standard deviation, σtot, and expanded measurement uncertainty, U
11 Information to be recorded
11.1 General
11.2 Noise source under test
11.3 Test room
11.4 Instrumentation
11.5 Acoustical data
12 Test report
Annex A
A.1 General
A.2 Instrumentation and measuring equipment
A.2.1 General
A.2.2 Test sound source type
A.2.2.1 General
A.2.2.2 Test sound source directivity
A.3 Installation of test sources and microphones
A.3.1 Anechoic rooms
A.3.2 Hemi-anechoic rooms
A.3.2.1 General
A.3.2.2 Size of reflecting plane
A.3.2.3 Sound absorption coefficient
A.3.3 Microphone traverse
A.4 Test procedures
A.4.1 Generation of sound
A.4.2 Measurement of sound pressure level
A.4.3 Determination of deviations from the inverse square law
A.4.3.1 Equation for estimation of sound pressure levels based on the inverse square law
A.4.3.2 Deviations from the inverse square law
A.5 Qualification procedure
Annex B
B.1 General
B.2 Properties of reflecting plane
B.2.1 General
B.2.2 Size
B.2.3 Sound absorption coefficient
B.3 Procedure using two measurement spheres or hemispheres with different radii (two-surface method)
B.3.1 Test sound source
B.3.2 Procedures
Annex C
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
Annex E
Annex F
Annex G
Annex H
Annex I
I.1 General
I.2 Considerations on the total standard deviation, σtot
I.3 Considerations on σomc
I.4 Considerations on σR0
I.4.1 General
I.4.2 Contributions to the uncertainty, σR0
I.4.2.1 General
I.4.2.2 Sound pressure measurement repeatability
I.4.2.3 Measurement surface area
I.4.2.4 Background noise correction
I.4.2.5 Meteorological corrections
I.4.2.6 Environmental reflections
I.4.2.7 Sound level meter
I.4.2.8 Sampling
I.4.2.9 Angle
I.4.2.10 Measurement method
I.4.2.11 Typical value for σR0
I.4.2.12 Measurement in frequency bands
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
I.7.1 General
I.7.2 Contributions to the uncertainty, σomc
I.7.3 Contributions to the uncertainty, σR0
I.7.4 Combined standard uncertainty
Bibliography
Amendment 1
ISO 3745:2012/Amd 1:2017
Annex A (normative) General procedures for qualification of anechoic and hemi-anechoic rooms
A.1 General
A.2 Qualification criteria
A.2.1 General
A.2.2 Maximum allowable deviations from inverse square law
A.2.3 Frequency range to be qualified
A.2.4 Maximum qualified radius
A.2.5 Properties of the reflecting plane in a hemi-anechoic room
A.3 Installation of test sound sources and microphone traverses
A.3.1 Test sound source requirements
A.3.2 Test sound source location
A.3.2.1 General
A.3.2.2 Test sound source location in hemi-anechoic room
A.3.3 Microphone traverse paths
A.4 Test procedure
A.4.1 Analysis bandwidth
A.4.2 Generation of sound
A.4.3 Spatial resolution of the measurement points
