"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. The acceptance limits for class LS sound calibrators are based on the use of a laboratory standard microphone@ as specified in IEC 61094-1@ for demonstrations of conformance to the requirements of this document. The acceptance limits for class 1 and class 2 sound calibrators are based on the use of a working standard microphone@ as specified in IEC 61094-4@ for demonstrations of conformance to the requirements of this document. To promote consistency of testing of sound calibrators and ease of use@ this document contains three normative annexes ?C Annex A ""Pattern evaluation tests""@ Annex B ""Periodic tests""@ Annex C ""Pattern evaluation report""@ and two informative Annexes ?C Annex D ""Relationship between tolerance interval@ corresponding acceptance interval and the maximum-permitted uncertainty of measurement"" and Annex E ""Example assessments of conformance to specifications of this document"". This document does not include requirements for equivalent free-field or random-incidence sound pressure levels@ such as may can be used in the overall sensitivity adjustment of a sound level meter. A sound calibrator can provide other functions@ for example@ tonebursts. Requirements for these other functions are not included in this document. "