BS 4196-5:1981

National foreword
Cooperating organizations
Method
0.1 Related International Standards
0.2 Synopsis of ISO 3745
0.3 Introduction
1 Scope and field of application
2 References
3 Definitions
4 Test room requirements
5 Instrumentation
6 Installation and operation of source
7 Determination of mean-square pressure
8 Calculation of sound power level
9 Information to be recorded
10 Information to be reported
Annexes
A Test room qualification procedures
B Recommended array of microphone positions in a free
     field
C Basic array of microphone positions in a free field
     over a reflecting plane
D Coaxial circular paths in parallel planes for
     microphone traverses in a free field over a
     reflecting plane
E Calculation of directivity index and directivity
     factor
F System for microphone traverses along meridional
     paths in a free field
G Guidelines for the design of test rooms
H Examples of suitable instrumentation systems
I Guidelines for the detection of impulsive noise
Tables
1 International Standards specifying various methods
     for determining the sound power levels of machines
     and equipment
2 Uncertainty in determining sound power levels of
     sound sources in anechoic rooms
3 Uncertainty in determining sound power levels of
     sound sources in semi-anechoic rooms
4 Relative tolerances for the instrumentation system
5 Corrections for background sound pressure levels
6 Maximum allowable differences between the measured
     and theoretical values
7 Microphone positions
8 Recommended microphone positions when the source
     emits predominant pure tones
Figures
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Describes two laboratory methods for determining the sound power level of a source. It gives requirements for the test room, as well as the source location, operating conditions and instrumentation. Techniques are specified for obtaining an estimate of the surface sound pressure level from which the weighted sound power level of the source as well as the sound power level in octave or one-third octave bands may be calculated. Intended to prescribe techniques for acoustical measurements that may be used in test codes for particular types of equipment.