10. The proper functioning of the sound level meters and sound calibrators described in Division I of this Chapter must be verified by a laboratory performing traceable calibrations at the intervals determined by the manufacturer. Failing the indication by the manufacturer of such verification, the proper functioning of those instruments must be verified as follows:(1) for a sound level meter, in the 24 months preceding its last use;
(2) for a sound calibrator, in the 12 months preceding its last use.