German legal provisions governing hearing protectors
Irrespective of the level of noise exposure at workplaces, the German Occupational Health and Safety Act (ArbSchG) states that it must be avoided or reduced to the greatest possible extent. The state of the art serves as the point of reference for this purpose. If one of the upper action values of the German Ordinance on noise and vibration protection is violated, the employer must draw up a plan of technical and organizational noise abatement measures, and implement them.
If the noise exposure cannot be avoided, suitable hearing protection must be selected. The Ordinance on noise and vibration protection requires the employer to offer his employees suitable hearing protection when the lower action values for exposure are exceeded (LEX,8h > 80 dB(A) and LpC,peak > 135 dB(C)). Once the upper action values are reached, the use of hearing protection as specified is a requirement (LEX,8h ≥ 85 dB(A) and LpC,peak ≥ 137 dB(C)).
The hearing protection selected must be such that the exposure limit values at the user's ear are observed in consideration of the sound attenuation of the hearing protector. For the residual level L’ at the ear, the following therefore apply: L’EX,8h ≤ 85 dB(A) and L’pC,peak ≤ 137 dB(C). The HML check is used as the default method in Germany for calculation of the residual level at the ear. It must first be determined whether the noise at the workplace is generally of high or medium frequency (HM class) or low frequency (L class). Accordingly, either the M value or the L value of the hearing protector is then used as the sound attenuation.
Derating values must also be applied for use in the field. These take account of the fact that the attenuation values measured during type testing of the hearing protector are generally not reached in industrial use. Besides ageing and soiling of the products, a particular reason for this is incorrect or careless fitting of the hearing protector.
More detailed information on the HML check and derating values for use in the field can be found in DGUV Regel 112-194 (so far: BGR/GUV-R 194) and DGUV Information 212-024 (so far: BGI/GUV-I 5024). This selection method also forms the basis for the IFA selection program (see below) and the IFA list of approved products contained in DGUV Regel 112-194.
For custom-moulded earplugs which are individually formed to the wearer's ear canal, both the DGUV publications and the state technical rules governing noise pursuant to the Ordinance on noise and vibration protection (Section 6.2.3) require a fitting check to be performed following delivery (within six months) and subsequently at regular intervals of not more than three years. Only by this means can the correct fitting of custom-moulded earplugs be assured and thus also the sound attenuation as determined in the type testing and documented in the user information for the product concerned. Comprehensive information on this topic can be found in the information module provided by the specialized field of hearing protection within the DGUV's "Personal protective equipment" expert committee (download module (PDF, 45 kB).