Acoustics case study

Noise at Work


It is an established fact that excessive noise causes damage to hearing. If the exposure is brief, the damage may be temporary. However in the workplace exposure can be repetitive and long term which can result in permanent hearing damage and deafness. In 1989 the Noise at Work Regulations were introduced. These regulations are now superseded by The Control of Noise at Work Regulations 2005. The new regulations impose tighter limits on noise exposure to reduce the risk of noise induced deafness of employees, and place more emphasis on the need to take action to reduce exposure levels.
There are new “Action Levels” defined in the Regulations. These are:

  • Lower Action Value A daily/weekly noise exposure of 80 dB LEp,d
  • Upper Action Value A daily/weekly noise exposure of 85 dB LEp,d
  • Exposure Limit Value A maximum exposure of 87 dB LEp,d


There is a duty on employers to reduce the risk of excessive exposure to noise for their employees. The risk must be assessed and employees informed of it. Where action is shown to be needed, a noise control action plan must be implemented.

There are various processes that can be used to assess noise:

  • Noise at Work risk assessment
  • Noise dosimetry
  • Advice on hearing protection
  • Design of noise control measures
  • Design of buildings to contain/reduce noise
  • Vibration monitoring
  • Action plans for noise control


The assessment involved a survey, which was conducted over one day, can be described in two main parts:
The first part involved a noise survey at locations across the site with the aim of generating a ‘noise map’ of the facility. This enabled quick identification of the noise ‘hotspots’ and demonstrates the overall noise climate in different areas.

Secondly, we assessed the noise exposure of individual employees during a typical working shift by attaching noise doseBadges to the shoulders of employees for the minimum of an hour while they carried out typical work tasks.

Operational noise levels were monitored at various positions around the site and shown on a Noise Map. Noise doseBadges were fitted to the shoulders of employees for periods ranging from 3hrs to 3.5hrs. The doseBadges were set to measure while the wearer was going about their normal work tasks. Post processing enabled the calculation of the personal noise dose of each employee over their working shift. From the noise map we were able to provide demarcation lines within the workplace and advice on the signage required to show what protective equipment was required in each area. The map and doseBadge information was used to produce rota patterns that avoided employees exceeding legal maximum exposure times.