IEEE 85-1973

1 Scope
2 Definitions and terms
2.1 Sound pressure level
2.2 A-weighted sound level
2.3 Octave band level
2.4 Sound power level
2.5 A-weighted sound power level
2.6 Prescribed surface
2.7 Equivalent radius
2.8 Reference distance
2.9 Reference radius
2.10 Background level
2.11 Mean sound pressure level or mean sound level
2.12 Machine
2.12.1 Small machine
2.12.2 Medium machine
2.12.3 Large machine
3 Installation and operation
3.1 Machine mounting
3.1.1 Field installation
3.1.2 Test mounting
3.1.3 Multiunit machines
3.2 Operating condition
3.2.1 No-load test
3.2.2 Full-load test
4 Measuring instruments
4.1 Sound level meter
4.2 Band filter networks
4.3 Level recorder
4.4 Sound measuring systems
4.4.1 Microphone
4.4.2 Interconnecting cable
4.4.3 Microphone signal amplifier
4.4.4 Frequency analyzer
4.5 Calibration
4.6 System check out
4.7 Electrical characteristic measurement
         instrumentation
5 Test environment
5.1 Free field over a reflecting plane
5.1.1 Free-field conditions in a test room
5.1.2 Other free-field situations
5.2 Reverberant field
5.3 Semireverberant field
5.4 Test to determine type of environment
5.5 Background level
6 Quantities to be reported
6.1 Standard
6.2 Additional
7 Methods of measurement
7.1 Free field over a reflecting plane
7.1.1 Location of measurement points
7.1.1.1 Small machines
7.1.1.2 Medium machines
7.1.1.3 Large machines
7.1.2 Test procedure
7.1.3 Measurement corrections
7.1.4 Calculation of the mean level
7.1.5 Calculation of A-weighted mean sound level
         using octave band mean sound pressure levels
7.1.6 Calculation of the A-weighted mean sound level
         at a reference distance for the condition of a
         free field over a reflecting plane
7.1.7 Calculation of the A-weighted sound power level
7.1.8 Calculation of the octave band sound pressure
         level at the reference distance for the
         condition of a free field over a reflecting
         plane
7.2 Reverberant field
7.2.1 Reference sound source
7.2.2 Location of measurement points
7.2.3 Test procedure
7.2.4 Measurement corrections
7.2.5 Calculation of mean level
7.2.6 Calculation of the sound power level in octave
         bands
7.2.7 Calculation of the mean sound pressure levels
         in octave bands at the reference distance for
         the conditions of a free field over a
         reflecting plane
7.2.8 Calculation of the A-weighted mean sound level
         at a reference distance for the condition of a
         free field over a reflecting plane
7.2.9 Calculation of A-weighted sound power level
7.3 Semireverberant field
7.3.1 Reference sound source
7.3.2 Location of measurement points
7.3.3 Test procedure
7.3.4 Measurement corrections
7.3.5 Calculation of the mean level
7.3.6 Calculation of the sound power level in octave
         bands
7.3.7 Calculation of the mean sound pressure levels
         in octave bands at the reference distance for
         conditions of a free field over a reflecting
         plane
7.3.8 Calculation of the A-weighted mean sound level
         at the reference distance for the condition of
         a free field over a reflecting plane
7.3.9 Calculation of A-weighted sound power level
8 Test report
Tables
1 Preferred frequencies for acoustical
         measurements
2 Corrections to be applied to obtain A-weighting
Figures
1(A) Prescribed points, small machines
1(B) Six-point hemisphere, small machines
2(A) Prescribed points, medium machines
2(B) Twelve-point hemisphere, medium machines
3 Prescribed points, large horizontal machines
4 Prescribed points, large vertical machines

Covers approved methods for reporting results and conducting tests to effect the uniform determination of rotating electric machine sound under steady-state conditions with an accuracy of 3dB tested in the following acoustical environments: free field, reverberant field, semireverberant field.