Sound attenuation of hearing protectors in workplaces II

Project No. BGIA 4119


completed 09/2007


Directive 2003/10/EC of the European Parliament and of the Council of 6 February 2003 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise) sets out limit values for the first time. This directive was transposed into German law on 9 March 2007 in the form of the Occupational Health and Safety Ordinance on Noise and Vibration (LärmVibrationsArbSchV). For application of the exposure limit values, consideration was to be given in the directive to the attenuating action of the employee's personal hearing protection during measurement of the employee's effective exposure to noise. The laboratory sound attenuation value which the manufacturer is required to state is rarely attained at the workplace. Complex measurements conducted under a hearing protector are seldom possible or advantageous. For transposition of the directive governing application and consideration of hearing protectors, the Federal Ministry of Labour and Social Affairs (BMAS) enlisted the support of the Personal Protective Equipment (PPE) expert committee of the BG Central office for health and safety at work (BGZ). The expert committee has already drawn up a guidance document. In order for the state of the art in hearing protector technology to be implemented by means of the guidance document, the PPE expert committee required up-to-date values for the sound attenuation of hearing protectors in day-to-day industrial activity. The objective of this project was to determine such values.


Measurements of the sound attenuation were conducted in the audiomobiles of the BG for the metalworking industry in southern Germany (BGMS) in member companies of the BGMS and of the BG for the mechanical engineering and metalworking industry (MMBG). Preparation of the software and hardware, analysis of the measured data and comparison with the laboratory values from the hearing protector test were conducted by the BGIA - Institute for Occupational Safety and Health. Joint reporting involving the PPE expert committee, BGMS and MMBG was planned.


During the 24 months over which the project ran, a total of 829 measurements were performed in 46 plants. Values for noise attenuation under real-case conditions were obtained from a sufficiently large random sample for fourteen hearing protector products. Comparison of the averages of these data records with those from laboratory measurements performed for type tests revealed an inferior sound attenuation for all products in plant use.
The difference between the respective sound attenuation values varied strongly according to the type of hearing protector. Altogether, this study confirms the previous study on the same subject which was conducted in 1989.
For the individual hearing protector types, the differences determined in this way were considered in the form of correction values in recommendations for the selection of hearing protectors, for example in the list of approved products and the BGIA's selection program for hearing protectors, BG Rule 194, and at international level, in the EN 458 standard, "Hearing protectors - Recommendations for selection, use, care and maintenance".

Last Update:



Financed by:
  • Hauptverband der gewerblichen Berufsgenossenschaften (HVBG)
Research institution(s):
  • Maschinenbau- und Metall-Berufsgenossenschaft
  • Berufsgenossenschaft Metall Süd
  • Berufsgenossenschaftliches Institut für Arbeitsschutz - BGIA

-cross sectoral-

Type of hazard:



Lärm, Persönliche Schutzausrüstung

Description, key words:

hearing protectors, sound attenuation, effectiveness, new noise limit value