Gives electroacoustical performance specifications for three kinds of sound measuring instruments:- a conventional sound level meter that measures exponential time-weighted sound level;- an integrating-averaging sound level meter that measures time-average sound level; and- an integrating sound level meter that measures sound exposure level.A single instrument may make any, or all, of the three kinds of measurements.Two performance categories, class 1 and class 2, are specified in this standard. In general, specifications for class 1 and class 2 sound level meters have the same design goals and differ mainly in the tolerance limits and the range of operational temperatures. Tolerance limits for class 2 specifications are greater than, or equal to, those for class 1 specifications.Sound level meters conforming to the requirements of this standard have a specified frequency response for sound incident on the microphone from one principal direction in an acoustic free field or from random directions.