This International Standard describes the determination of the acoustical quantities, especially the type and locations of sound pressure level measurements to be conducted, the time sampling and frequency analysis required and the special characteristics of the noise to be considered. The purpose is to allow an assessment of the noise in the working environment with respect to its various effects on the worker as a result of daily habitual exposure. This International Standard is intended to be used by appropriate authorities responsible for specifying and monitoring compliance with noise limits at the workplace and for deciding on the need for hearing conservation programmes and noise reduction measures. It does not by itself specify or recommend acceptable noise limits. The standard does not specify statistical sampling procedures to characterize the noise exposure of groups, although references to such procedures are included in the bibliography. The applications of the measurement results are described with respect to the effects of noise on hearing, interference with communication and other effects of noise. Special requirements for the description of infrasound and ultrasound exposure are included. Applications of the Standard to evaluate effects of the noise on health, working efficiency, wellbeing and the audibility of warning signals are summarized in Annex A. Annex B gives examples of equivalent continuous A-weighted sound pressure level calculations. Annex C discusses calculation of the rating level including tone and impulsive adjustment. Annex D specifies classes of accuracy for noise measurements. All the annexes are informative.