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e-CFR data is current as of November 27, 2020

Title 40Chapter ISubchapter GPart 211Subpart B → §211.204-4

Title 40: Protection of Environment
Subpart B—Hearing Protective Devices

§211.204-4   Supporting information.

The following minimum supporting information must accompany the device in a manner that insures its availability to the prospective user. In the case of bulk packaging and dispensing, such supporting information must be affixed to the bulk container or dispenser in the same manner as the label, and in a readily visible location.

(a) The mean attenuation and standard deviation values obtained for each test frequency according to §211.206, and the NRR calculated from those values. For “muff” type protectors with various use positions, the positions providing higher NRR values shall be identified, and their associated NRR values listed in bold type.

(b) The following statement, example and cautionary note: “The level of noise entering a person's ear, when hearing protector is worn as directed, is closely approximated by the difference between the A-weighted environmental noise level and the NRR.


1. The environmental noise level as measured at the ear is 92 dBA.

2. The NRR is (value on label) decibels (dB).

3. The level of noise entering the ear is approximately equal to [92 dB(A)—NRR] dB(A).

Caution: For noise environments dominated by frequencies below 500 Hz the C-weighted environmental noise level should be used.”

(c) The month and year of production, which may be in the form of a serial number or a code in those instances where the records specified in §211.209(a)(1)(iv) are maintained;

(d) The following statement: “Improper fit of this device will reduce its effectiveness in attenuating noise. Consult the enclosed instructions for proper fit”;

(e) Instructions as to the proper insertion or placement of the device; and

(f) The following statement: “Although hearing protectors can be recommended for protection against the harmful effects of impulsive noise, the Noise Reduction Rating (NRR) is based on the attenuation of continuous noise and may not be an accurate indicator of the protection attainable against impulsive noise such as gunfire.”

[44 FR 56127, Sept. 28, 1979, as amended at 45 FR 8275, Feb. 6, 1980]

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