IEC 60942:2003

Specifies the performance requirements for three classes of sound calibrator. Sound calibrators are designed to produce a known effective sound pressure level or levels at a specified frequency or frequencies when coupled to specified models of microphone or specified configurations, for example, with or without protective grid.

Specifies requirements for sound calibrators with respect to their immunity to power- and radio-frequency fields and to electrostatic discharge, and the permitted radio-frequency emissions, together with the test procedures to demonstrate conformance to the specifications of this standard.

IEC 60942:2017 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. This fourth edition cancels and replaces the third edition published in 2003, of which it constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) deletion of the class designations, class LS/C, class 1/C and class 2/C; b) addition of two further class designations, class LS/M and class 1/M, specifically for pistonphones; c) addition of an amended criterion for assessing conformance to a specification: conformance is now demonstrated when (a) measured deviations from design goals do not exceed the applicable acceptance limits and (b) the uncertainty of measurement does not exceed the corresponding maximum-permitted uncertainty; d) modification to the short-term level fluctuation test of the sound pressure level stability; e) change to some environmental test conditions to avoid icing; f) addition of an alternative test for immunity to radio-frequency fields using transverse electromagnetic (TEM) waveguides.