Noise at work is a nuisance that can be considered from different angles, possibly inducing (variable depending on the context):
- with regard to workers:
- conditions for carrying out their tasks leaving something to be desired (e.g. to concentrate)
- difficulties in oral communication (viva voce or by telephone: to understand and be heard), not only when discretion[1] or confidentiality[2] are desirable
- stress, fatigue and risks to physical integrity, when audible warning signals are not correctly perceived and risks of hearing loss
- with regard to the company that employs workers:
- degraded working atmospheres
- decreases in the quality of productions
- absenteeism and recruitment difficulties
- administrative complications and costs in the event of proven occupational deafness
It is therefore permissible to consider the regulation of noise at work as a good thing for all, being - in France - based on specifications concerning:
- the sound levels to which employees may be exposed
- the minimum characteristics of noisy premises, in terms of soundproofing
Regulations for noise at work: specifications concerning the sound levels to which employees may be exposed
In terms of regulations for noise at work, concerning the sound levels to which employees may be exposed, Directive 2003/10/EC of the European Parliament and of the Council of 6 February 2003 on the minimum health and safety requirements relating to the exposure of workers to the risks due to physical agents (noise), transposed into French law, constitutes the reference document for:
- the peak sound pressure (ρpeak) i.e. the maximum value of the instantaneous sound pressure measured with frequency weighting C
- the daily noise exposure level (LEX,8h ) (dB(A) ref. 20 μPa) i.e. the time-weighted average of the noise exposure levels for a nominal eight-hour working day (taking account of impulsive noise, if any)
- the weekly noise exposure level (LEX,8h) i.e. the time-weighted average of the daily noise exposure levels for a nominal week of five eight-hour working days
Exposure limit values and exposure action values in relation to daily noise exposure levels and peak sound pressure are set at:
- exposure limit values: LEX,8h = 87 dB(A) and ρpeak = 200 Pa i.e. 140 dB (C) ref. 20 μPa respectively
- upper exposure values triggering the action: LEX,8h = 85 dB(A) and ρpeak = 140 Pa i.e. 37 dB (C)ref. 20 μPa) respectively
- lower exposure values triggering the action: LEX,8h = 80 dB(A) and ρpeak = 112 Pa i.e. 135 dB (C) ref. 20 μPa respectively
Regulations for noise at work: specifications concerning the minimum characteristics of noisy premises, in terms of soundproofing
In terms of regulations for noise at work, concerning the minimum characteristics of noisy premises, in terms of soundproofing, the Order of 30 August 1990 taken for the application of Article R. 235-11 of the Labor Code and relating to the acoustic correction of work premises is the reference document, for the decrease in sound level by doubling the distance to the source DL. The minimum values are set, according to the floor area of room S (in square meters) at:
- in the case of a room empty of any machine or production facility:
| floor area of room S | below 210 m2 | between 210 m2 and 4600 m2 | above 4600 m2 |
|---|---|---|---|
| DL in dB(A) | 2 | 1,5 log10 (S) - 1,5 | 4 |
| remark | - | S in m2 in the formula | - |
- in the case of premises after installation of production machinery and equipment
| floor area of room S | below 210 m2 | between 210 m2 and 1000 m2 | above 1000 m2 |
|---|---|---|---|
| DL in dB(A) | 3 | 1,5 log10 (S) - 0,5 | 4 |
| remark | - | S in m2 in the formula | - |
The above specifications are applicable for the construction or fitting out of work premises, where machines and devices likely to expose workers to a daily noise exposure level greater than 85 dB (A) must be installed, whether a predictive acoustic study shows it, or such a study is lacking.
Area of intervention of ITS in relation to the regulation of noise at work
The areas of intervention of ITS in relation to the regulation of noise at work vary according to the context:
- on-site measurements of the physical parameters basing the specified limits:
- sound pressure levels (on the one hand: peak and on the other hand: equivalent continuous)
- decrease in sound level by doubling the distance to the source
Such sound metrology can be carried out with own-owned acoustic measurement means by a human resource duly qualified in physical measurements (specialized in instrumental techniques), with extensive experience in the field of noise-related data acquisition and processing, as required for a diagnosis at workplaces, e.g. relation to dedicated standards
- ISO 9612 Acoustics - Determination of occupational noise exposure - Engineering method
- NF EN ISO 14257 Acoustics - Measurement and parametric description of spatial sound distribution curves in workrooms for evaluation of their acoustical performance
The results of the sound level measurements carried out can give rise to the preparation of noise maps, and can - like those concerning the spatial decay rates[3], be compared to the regulatory limits for a compliance review ; in addition to regulatory impositions, ITS can measure the reverberation time of work premises[4]
- in the case of non-compliance of measurement results with regulatory specifications, (in the context of an engineering assignment) identification of areas for improvement and development of action plans:
- calculations for sound propagation, absorption and transmission
- simulation of noise or reverberation diminution efficiency
- reduction of noise at source: canopies for noisy equipment, soundproofing enclosures for machines and production lines, silencers
- limitation of the propagation of noise by means of acoustic screens (anti-noise walls) or soundproof cabins for staff
- reduction of the reverberation rooms by the implementation of sound-absorbing materials (e.g. soundproofing wall panels, acoustic ceiling tiles and baffles suspended from the underside of roofs)
ITS has means of simulation and calculation in terms of predictive acoustics (some: analytical, others: based on ray tracing) available to a qualified human resource in building physics, with long experience of studies relating to noise reduction in an industrial environment.
Can one imagine that Research and Development, or even compatibility tasks can be carried out properly in a sound environment characterized by a sound pressure level of 80 dB(A) which would comply with the applicable noise regulations?
Because the regulations only provide minimum requirements, from the point of view of the safety and health of employees, it is permissible, in some contexts, to consider being a little more ambitious in terms of acoustic comfort of the work premises and workplaces ; recourse can then be made to ITS for a personalized study of the acoustic comfort of all workplaces (including individual or collective offices, i.e. open spaces and associated spaces such as company restaurants for which there are reference standards, although not - in general - of mandatory application[5]).
In addition, in addition to its consulting activity, ITS markets all the soundproofing solutions (components and systems) for workspaces that meet regulatory requirements relating to noise.
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[1] situation obtained when an effort is required to understand the content of a conversation; then, the conversation is not a source of distraction
[2] situation obtained when even with an effort to understand a conversation, it remains incomprehensible
[3] slope in decibels of the spatial sound decay curve in a given distance range, when the distance to the source doubles
[4] time interval required for the reduction in a ratio of 1 million to 1 of the sound pressure after interruption of a sound source
[5] Acoustics - Offices and associated areas - Acoustic performance levels and criteria by type of area