GB/T 42553-2023 Electroacoustics—Methods to determine corrections to obtain the free-field response of a sound level meter

Scope

This document provides information on the correction values required for sound level meters in a certain frequency range during periodic testing according to IEC 61672-3. These correction values include:
—— Correction values for typical effects of reflection from the sound level meter housing and sound diffraction around the microphone;
—— Correction values for deviations between the typical microphone frequency response and the uniform frequency response when the actual microphone response cannot be measured;
—— Correction values for the effects of windshields or any other accessories specified as part of the nominal operating configuration of the delivered sound level meter on the typical microphone frequency response.
This document includes a discussion of the measurement uncertainties of the required correction values. In some cases, the maximum allowable extended measurement uncertainties are provided for manufacturers or testing laboratories. These maximum allowable extended uncertainties do not include any components due to differences in different samples of artifacts (such as microphones or windshields). It should be noted that if each correction value introduces a large measurement uncertainty, these large individual uncertainties can lead to non-compliance with the maximum allowable extended measurement uncertainties given in Table A.1 of GB/T 3785.1-2023 when considering the configuration of the tested sound level meter, thus making the sound level meter non-compliant with GB/T 3785.1.
Additionally, this document describes the method for determining these correction values in the frequency range of interest and explains the adjustment values on the calibration check frequency provided by the sound level meter manufacturer (as required by IEC 61672-3).
When the sound level meter manufacturer recommends the use of sound calibrators, comparison couplers, or electrostatic exciter for periodic testing of the sound response

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