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Safeguard OSH Solutions - Thomson Reuters

Safeguard OSH Solutions - Thomson Reuters

The noise spectrum

Reducing noise harm in the workplace requires a multifaceted approach, says DAVID WARRINGTON.

Thousands of New Zealanders will be at risk of hearing damage from noise at work, making noise one of the most widespread occupational hazards in the country.

Yet many people are unaware of the risks from noise. Even more concerning is that many people are aware of the risks but choose to ignore them. How many times have you heard “Noise doesn’t affect me” or “I’m already deaf so it doesn’t matter”?

Hearing damage, or what we call noise induced hearing loss (NIHL), may occur with no obvious signs or symptoms. It’s rarely painful and may not even be noticeable for many years, which may partly explain the casual approach to noise that is unfortunately all too common.

Employers and employees have a duty of care to themselves and others to maintain a safe workplace and reduce hazards – including noise – as far as reasonably practicable. So how can we address workplace noise?

First we must identify whether a noise hazard exists. Average noise levels above 85dB(A) over a standardised 8-hour working day and instantaneous peak noise levels above 140dB(C/Z) are considered to be hazardous.

We then need to answer four key questions:

  • • 
    Who is at risk? Individuals at risk of hearing damage must be identified.
  • • 
    By how much are they over-exposed? The magnitude of the noise must be measured and level of exposure assessed for all exposed personnel.
  • • 
    What are the causes of exposure? Noisy equipment, processes, tasks and areas must be identified.
  • • 
    What can be done about it? The hierarchy of controls must be followed to reduce the noise.

While necessary noise controls are being put in place, hearing protection must usually also be worn. Unfortunately many organisations approach this process in the reverse order: if noise is considered to be a problem, hearing protectors are provided as the final (and only) solution.

This does not of course address the real issue, since hearing protection does not reduce the amount of noise in the workplace. Certainly hearing protection has an important role in the reduction of the risk of noise induced hearing loss, but provision of PPE does nothing to reduce the hazard itself.

Furthermore, the true effectiveness of PPE is virtually impossible to assess accurately, and is highly dependent on user training, motivation, and utilisation. As a result, the level of protection provided by a pair of earmuffs or earplugs in practice is usually significantly lower than that specified by the manufacturer.

To manage noise effectively, we must target the hazard (the noise at source) rather than the risk (exposure to that noise) and here the hierarchy of controls applies to noise just as it does to any other hazard.

The preferred option is to eliminate the hazard completely, but in most occupational situations, removing all noise by removing the noise sources is rarely practical. Substituting the noisy process, task, or tool with a quieter one that does the same job is the next approach, and this is often achieved over time by means of a “buy quiet” programme, where the noise level of new machinery, equipment, and tools is considered as part of the purchasing process.

The next step, engineering noise control – which may include regular maintenance of equipment, use of low-noise fittings, silencers, damping materials, enclosures and sound insulation, absorptive materials, and appropriate location of noise source – is widely used where elimination and substitution cannot be applied or where these approaches take some time to implement. Engineering noise control solutions range from simple off-the-shelf fittings to highly complex designs requiring the expertise of specialist acoustical consultants.

Administrative noise control can also play a key role in noisy workplaces but here we are dealing with reducing the risk rather than reducing the hazard. Administrative noise controls may include limiting the time that people can do noisy tasks, carrying out high-noise tasks at times when fewer people are present, restricting certain operations to particular times, and restricting access to areas where noise is present.

So reducing noise in the workplace to minimize the risk of NIHL is a multi-faceted process which requires input from a range of personnel. Noise assessments should be carried out by competent noise assessors who can answer such questions in detail. They would have detailed training in how to achieve this, typically based upon the training requirements of AS/ NZS1269 – 2005 Occupational Noise Management.

However the need for appropriate training does not end with the noise assessor themselves.

In order to satisfactorily address workplace noise, training of some form must extend to everyone on the site – managers, supervisors, OHS personnel, buyers, and of course the exposed workers themselves. If noise hazard training does not permeate through every part of the organisation, workers will continue to go deaf.

We know why noise is a problem. We know what effects noise can have on the human body. We know what we can do about it in most cases. And yet the incidence of NIHL continues to increase in workplaces.

Only a shift in the fundamental approach to noise management can really make a significant and ongoing difference, and the key to this is education at all levels.

DAVID WARRINGTON is the services manager at NVMS (Noise and Vibration Measurement Systems Pty Ltd) in Perth.

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