NS EN ISO 3746 : 2010

Committees responsible
National foreword
Foreword
Introduction
Method
1 Scope
2 Normative references
3 Definitions
4 Acoustic environment
5 Instrumentation
6 Installation and operation of source under test
7 Measurement of sound pressure levels
8 Calculation of A-weighted surface sound pressure
      level and A-weighted sound power level
9 Information to be recorded
10 Information to be reported
Annexes
A (normative) Qualification procedures for the
      acoustic environment
B (normative) Microphone array on the hemispherical
      measurement surface
C (normative) Microphone array on the parallelepiped
      measurement surface
D (informative) Guidelines for the detection of
      impulsive noise
E (informative) Bibliography
Tables
0.1 Overview of International Standards for
      determination of sound power levels of noise sources
      using enveloping surface methods over a reflecting
      plane and giving different grades of accuracy
1 Estimated upper values of the standard deviations of
      reproducibility of A-weighted sound power levels
      determined in accordance with this International
      Standard
A.1 Approximate values of the mean sound absorption
      coefficient alpha
B.1 Coordinates of key microphone positions (4,5,6,10)
      and additional microphone positions (14,15,16,20)
B.2 Coordinates of microphone positions (4,5,6,10) for
      sources emitting discrete tones
Figures
1 Examples illustrating reference boxes and
      characteristic source dimensions d0 with respect to
      the origin of the coordinate system Q
A.1 Environmental correction K2A, in decibels
B.1 Microphone array on the hemisphere - key microphone
      positions
B.2 Microphone array on the hemisphere
B.3 Plain view of a spherical measurement surface and
      microphone positions around a reference box adjacent
      to two reflecting planes
C.1 Procedure for fixing the specified microphone
      positions where a side of the measurement surface
      exceeds 3d
C.2 Example of a measurement surface and microphone
      positions for a small machine
C.3 Example of a measurement surface and microphone
      positions for a tall machine with a small base area
C.4 Example of a measurement surface and microphone
      positions for a long machine
C.5 Example of a measurement surface and microphone
      positions for a medium-sized machine
C.6 Example of a measurement surface and microphone
      positions for a large machine
C.7 Measurement surface (parallelpiped) with four
      microphone positions for floor-standing appliances
      placed against a wall
C.8 Measurement surface (parallelpiped) with three
      microphone positions for floor-standing appliances
      placed against two walls

Gives a method of measurement for sound pressure levels on a measurement surface which envelops the source so as to calculate the sound power level of the source of noise. Describes test environment and instrumentation requirements in addition to techniques for obtaining sound pressure level from which the sound power level of the source is calculated, giving results having a grade 3 accuracy.