BS 4196-6:1981

National foreword
Cooperating organizations
Method
0.1 Related International Standards
0.2 Synopsis of ISO 3746
0.3 Introduction
1 Scope and field of application
2 References
3 Definitions
4 Acoustic environment
5 Instrumentation
6 Installation and operation of source
7 Measurement of weighted sound pressure levels
8 Calculation of surface sound pressure level and
     sound power level
9 Information to be recorded
10 Information to be reported
Annex
A Test environment qualification procedure
National appendix
A Proposed amended text for clause 8
B Proposed amended text for the annex
Tables
1 International Standards specifying various methods
     for determining the sound power levels of machines
     and equipment
2 Uncertainty in determining A-weighted sound power
     level by the survey method
3 Co-ordinates of microphone positions in terms of
     distances from centre of hemisphere along three
     mutually perpendicular axes (x, y, z)
4 Correction for background noise
5 Approximate values of the mean acoustic absorption
     coefficient alpha
Figures
1 Microphone array on the hemisphere
2 Location of measurement positions on the
     parallelepiped
3 Environmental correction K in decibels

Lays down a survey method for measuring the weighted sound pressure levels at prescribed microphone positions around a noise source. The A-weighted sound power level of the source is calculated from the measured values. This method may be applied in situ to sources which cannot be moved to a special test environment.