(a) All hearing protective devices manufactured after the effective date of this regulation, and meeting the applicability requirements of Sec. 211.201, must be labeled according to this subpart, and must comply with the Labeled Values of mean attenuation.
(b) A manufacturer must take into account both product variability and test-to-test variability when labeling his devices in order to meet the requirements of paragraph (a) of this section. A specific category is considered when the attenuation value at the tested one-third octave band is equal to or greater than the Labeled Value, or mean attenuation value, stated in the supporting information required by Sec. 211.204-4, for that tested frequency. The attenuation value must be determined according to the test procedures of Sec. 211.206. The Noise Reduction Rating for the label must be calculated using the Labeled Values of mean attenuation that will be included in the supporting information required by Sec. 211.204-4. [47 FR 57717, Dec. 28, 1982]