This document specifies the performance requirements for three classes of sound calibrator:
class LS (Laboratory Standard), class 1 and class 2. Acceptance limits are smallest for
class LS and greatest for class 2 instruments. Class LS sound calibrators are normally used
only in the laboratory; class 1 and class 2 are considered as sound calibrators for field use.
A class 1 sound calibrator is primarily intended for use with a class 1 sound level meter and a
class 2 sound calibrator primarily with a class 2 sound level meter, as specified in
IEC 61672-1.