BS ISO 14878:2015 pdf download – Cycles — Audible warning devices — Technical specification and test methods.
4 Symbols and abbreviated terms AWD Audible warning device 5 Instrumentations 5.1 Instruments for acoustical measurement 5.1.1 General The apparatus used for measuring the sound pressure level shall be a sound level meter or equivalent measurement system meeting the requirements of class 1 instruments (inclusive of the recommended windscreen, if used). These requirements are described in IEC 61672-1. The entire measurement system shall be checked by means of a sound calibrator that fulfils the requirements of class 1 sound calibrators according to IEC 60942. Measurements shall be carried out using the time weighting “F” of the acoustic measurement instrument and the “A” frequency weighting curve also described in IEC 61672-1. When using a system that includes a periodic monitoring of the A-weighted sound pressure level, a reading should be made at a time interval not greater than 30 ms. The instruments shall be maintained and calibrated in accordance to the instructions of the instrument manufacturer. When no general statement or conclusion can be made about conformance of the sound level meter model to the full specifications of IEC 61672-1, the apparatus used for measuring the sound pressure level shall be a sound level meter or equivalent measurement system meeting the requirements of class 1 instruments as described in IEC 61672-3.
5.1.2 Calibration At the beginning and at the end of every measurement session, the entire acoustic measurement system shall be checked by means of a sound calibrator as described in 5.1.1. Without any further adjustment, the difference between the readings shall be less than or equal to 0,5 dB. If this value is exceeded, the results of the measurements obtained after the previous satisfactory check shall be discarded. 5.1.3 Compliance with requirements Compliance of the sound calibrator with the requirements of IEC 60942 shall be verified once a year. Compliance of the instrumentation system with the requirements of IEC 61672-3 shall be verified at least every two years. All compliance testing shall be conducted by a laboratory which is authorized to perform calibrations traceable to the appropriate standards.