Noise reduction at work: hierarchy of measures

The order: S, T, O, P

Section 7(1) requires noise to be prevented or reduced where it arises. Engineering measures take priority over organisational ones, and both take priority over personal hearing protection under section 8. DGUV Rule 112-194 (section 5.2) summarises this as the STOP principle.

Levels of protective measures against noise with examples from section 7(2) of the German Noise and Vibration Ordinance
Level	Meaning	Examples
S, substitution	Replace the loud process or equipment	quieter working methods, choosing noise-reducing equipment
T, technical	Reduce sound at the source and along its path	screens, enclosures, damping of airborne and structure-borne sound, noise-reducing design of workplaces, maintenance programmes
O, organisational	Limit the exposure	shorter exposure time, sufficient noise-free breaks
P, personal	Hearing protection when the levels before are not sufficient	earplugs and earmuffs

Noise reduction programme above the upper action value

If an upper action value is exceeded, the employer must draw up and carry out a programme of technical and organisational measures to reduce exposure (section 7(5)). The order under paragraph 1 and the measures under paragraph 2 are to be taken into account first. In addition, the areas concerned must be marked as noise areas.

Rest rooms

In rest rooms, noise exposure must be reduced as far as possible, taking into account their purpose and conditions of use (section 7(3)). This also applies to break rooms where workers are meant to recover from noise.

When hearing protection is still needed

If the lower action values are not met despite the measures under section 7(1), the employer must provide suitable personal hearing protection (section 8(1)). It does not replace technical and organisational measures but complements them. How to choose the attenuation is covered in When is hearing protection required? and in the hearing protection finder.

Questions for practice

Can the loud process be replaced by a quieter one, or is there quieter equipment?
Are screens, enclosures or damping possible at the machine, the workpiece or the room?
Are maintenance and condition of the machines behind excessive levels (bearings, gearboxes, loose parts)?
Can time in noise be limited, and are there noise-free breaks?
How much noise remains, and which hearing protection is enough for it?
Is everything documented in the risk assessment?

EU Directive and UK regulations

Directive 2003/10/EC, Article 5: risks from noise are eliminated at the source or reduced to a minimum; from the upper action value a programme of technical and/or organisational measures is carried out.
UK, Control of Noise at Work Regulations 2005, regulation 6: noise is eliminated at source or, if that is not reasonably practicable, reduced to as low a level as is reasonably practicable; from the upper action value a programme of organisational and technical measures applies, and hearing protection does not count as such a measure.

Frequently asked questions

What comes first: hearing protection or noise reduction?

Noise reduction. Noise is to be prevented or reduced where it arises; engineering measures take priority over organisational ones and both over hearing protection (section 7(1) of the German Noise and Vibration Ordinance).

What is the STOP principle?

The order of protective measures: substitution, technical, organisational and personal measures (DGUV Rule 112-194, section 5.2).

When is a noise reduction programme needed?

When an upper action value is exceeded (85 dB(A) or 137 dB(C)). The employer must draw up and carry out a programme of technical and organisational measures (section 7(5)).

Do the rules also cover break rooms?

Yes. In rest rooms, noise exposure must be reduced as far as possible (section 7(3)).

Noise reduction: the source first, hearing protection last