ISO 3744:2010
Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound pressure — Engineering methods for an essentially free field over a reflecting plane
ISO 3744:2010 specifies methods for determining the sound power level or sound energy level of a noise source from sound pressure levels measured on a surface enveloping the noise source (machinery or equipment) in an environment that approximates to an acoustic free field near one or more reflecting planes. The sound power level (or, in the case of noise bursts or transient noise emission, the sound energy level) produced by the noise source, in frequency bands or with frequency A-weighting applied, is calculated using those measurements.
The methods specified in ISO 3744:2010 are suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) defined in ISO 12001.
ISO 3744:2010 is applicable to all types and sizes of noise source (e.g. stationary or slowly moving plant, installation, machine, component or sub-assembly), provided the conditions for the measurements can be met.
The test environments that are applicable for measurements made in accordance with ISO 3744:2010 can be located indoors or outdoors, with one or more sound-reflecting planes present on or near which the noise source under test is mounted. The ideal environment is a completely open space with no bounding or reflecting surfaces other than the reflecting plane(s) (such as that provided by a qualified hemi-anechoic chamber), but procedures are given for applying corrections (within limits that are specified) in the case of environments that are less than ideal.
Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with ISO 3744:2010, for measurements made in limited bands of frequency and with frequency A-weighting applied. The uncertainty conforms to ISO 12001:1996, accuracy grade 2 (engineering grade).
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Scope
General
Types of noise and noise sources
Test environment
Measurement uncertainty
Normative references
Terms and definitions
Test environment
General
Criteria for background noise
Relative criteria
General
Frequency band measurements
A-weighted measurements
Absolute criteria
Statement of non-conformity with criteria
Criterion for acoustic adequacy of test environment
General
Criterion for environmental correction
Instrumentation
General
Calibration
Definition, location, installation, and operation of noise s
General
Auxiliary equipment
Noise source location
Mounting of the noise source
General
Hand-held machinery and equipment
Base-mounted, wall-mounted, and tabletop machinery and equip
Installation and mounting conditions for moving noise source
Operation of source during test
Reference box and measurement surface
Reference box
Measurement surface
General
Microphone orientation
Hemispherical measurement surface
Parallelepiped measurement surface
Cylindrical measurement surface
Combination measurement surface
Determination of sound power levels and sound energy levels
Microphone positions on the measurement surface
Hemispherical measurement surface
Parallelepiped measurement surface
Cylindrical measurement surface
Combination measurement surface
Determination of sound power levels
Measurement of sound pressure levels
Calculation of mean time-averaged sound pressure levels
Measurement surface with microphone positions or traverses u
Measurement surface with segments having unequal areas
Corrections for background noise
Calculation of surface time-averaged sound pressure levels
Calculation of sound power levels
Determination of sound energy levels
Measurement of single event time-integrated sound pressure l
Calculation of mean single event time-integrated sound press
Calculation of mean single event time-integrated sound press
Correction for background noise
Calculation of surface single event time-integrated sound pr
Calculation of sound energy levels
Calculation of apparent directivity indices
Calculation of apparent surface sound pressure level non-uni
A-weighted sound power level and sound energy level
Measurement uncertainty
Methodology
Determination of (omc
Determination of (R0
General
Round robin test
Modelling approach for (R0
Typical upper bound values of (R0
Total standard deviation (tot and expanded measurement uncertainty U
Information to be recorded
General
Noise source under test
Test environment
Instrumentation
Acoustical data
Test report
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Related Information
Similar Standards
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BS 7445-1:2003
Description and measurement of environmental noise, Guide to quantities and procedures
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BS 7445-2:1991
Description and measurement of environmental noise, Guide to the acquisition of data pertinent to land use
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BS 7445-3:1991
Description and measurement of environmental noise, Guide to application to noise limits
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BS EN 13477-1:2001
Non-destructive testing. Acoustic emission. Equipment characterization, Equipment description
Scope
General
Types of noise and noise sources
Test environment
Measurement uncertainty
Normative references
Terms and definitions
Test environment
General
Criteria for background noise
Relative criteria
General
Frequency band measurements
A-weighted measurements
Absolute criteria
Statement of non-conformity with criteria
Criterion for acoustic adequacy of test environment
General
Criterion for environmental correction
Instrumentation
General
Calibration
Definition, location, installation, and operation of noise s
General
Auxiliary equipment
Noise source location
Mounting of the noise source
General
Hand-held machinery and equipment
Base-mounted, wall-mounted, and tabletop machinery and equip
Installation and mounting conditions for moving noise source
Operation of source during test
Reference box and measurement surface
Reference box
Measurement surface
General
Microphone orientation
Hemispherical measurement surface
Parallelepiped measurement surface
Cylindrical measurement surface
Combination measurement surface
Determination of sound power levels and sound energy levels
Microphone positions on the measurement surface
Hemispherical measurement surface
Parallelepiped measurement surface
Cylindrical measurement surface
Combination measurement surface
Determination of sound power levels
Measurement of sound pressure levels
Calculation of mean time-averaged sound pressure levels
Measurement surface with microphone positions or traverses u
Measurement surface with segments having unequal areas
Corrections for background noise
Calculation of surface time-averaged sound pressure levels
Calculation of sound power levels
Determination of sound energy levels
Measurement of single event time-integrated sound pressure l
Calculation of mean single event time-integrated sound press
Calculation of mean single event time-integrated sound press
Correction for background noise
Calculation of surface single event time-integrated sound pr
Calculation of sound energy levels
Calculation of apparent directivity indices
Calculation of apparent surface sound pressure level non-uni
A-weighted sound power level and sound energy level
Measurement uncertainty
Methodology
Determination of (omc
Determination of (R0
General
Round robin test
Modelling approach for (R0
Typical upper bound values of (R0
Total standard deviation (tot and expanded measurement uncertainty U
Information to be recorded
General
Noise source under test
Test environment
Instrumentation
Acoustical data
Test report