Provides for four types of meter, viz. Types 0 and 1 for laboratory and precision use, Type 2 for general field applications, and Type 3 for field noise survey applications, with one or more frequency-weighting characteristics A, B and C and one or more time-weighting characteristics S, F, I and P. Specifies the directional frequency-weighting and amplifier, time-weighting, detector and indicator characteristics, and sensitivity to various environments, and includes electrical and acoustical tests. Is technically equivalent to IEC 651 and includes an annex showing deviations from IEC 651.