Division 2.1 Acoustic measurements

The apparatus used for measuring the sound level shall be a precision sound-level meter or equivalent measurement system meeting the requirements of class 1 instruments (inclusive of the recommended windscreen, if used). Those requirements are described in ‘IEC 61672-1:2002: Precision sound level meters’, second edition, of the International Electrotechnical Commission (IEC).

Measurements shall be carried out using the ‘fast’ response of the acoustic measurement instrument and the ‘A’ weighting curve also described in ‘IEC 61672-1:2002’. When using a system that includes a periodic monitoring of the A-weighted sound pressure level, a reading shall be made at a time interval not greater than 30 ms (milliseconds).

The instruments shall be maintained and calibrated in accordance with the instructions of the instrument manufacturer.