text Geneva International Organization for Standardization 1994 monographic 20 p. Describes three methods (the octave-band, HML and SNR methods) for estimating the A-weighted sound pressure levels effective when hearing protectors are worn. The methods are applicable to either the sound pressure level or the equivalent continuous sound pressure level of the noise. Although primarily intended for steady noise exposures, the methods are also applicable to noises containing impulsive components. They are not suitable for use with peak sound pressure level measurements. Acoustics