Whether it’s traffic in the street or a neighbour’s music, noise is part of everyday life. Usually, these sounds are at safe levels. But especially loud noise can damage your hearing, either permanently or temporarily.
Occupational noise-induced hearing loss (NIHL) is preventable. But according to the HSE, around 18,000 people in Britain suffer deafness, ringing in the ears or other ear conditions caused by excessive noise at work.
Symptoms and conditions
NIHL is caused either by prolonged exposure to excessive noise or extremely loud bursts of sound. Loud noise can damage the hair cells in your inner ear, reducing their ability to pick-up and transmit sound to the brain. Generally, hearing loss is gradual. By the time you notice it, it’s probably too late, so it’s important to prevent it from occurring in the first place.
Hearing loss caused by noise mainly affects hearing of sounds in the high frequencies. If noise exposure continues, this will spread to lower and higher frequencies too, leading to difficulty hearing speech.
Hearing loss is not the only condition caused by exposure to loud noise – it can also cause tinnitus. People often describe tinnitus as ringing in the ears, but different people can experience different sounds, including buzzing, humming or hissing. Some find it more distressing than the hearing loss.
Decibel is a measurement used to express a level of sound. Levels of noise as perceived by the human ear are usually expressed as an “A-weighted” decibel, or dB(A), to recognise that the ear is less sensitive to low frequencies of sound.
To give an idea of comparative levels of sound, a normal conversation is about 60 dB(A); a vacuum cleaner is around 70 dB(A); traffic on a busy road at a distance of 10m might be between 80 and 90 dB(A); while a chainsaw one metre away will be up to 120 dB(A). However, a chainsaw is not twice as loud as a conversation. Most of us perceive one sound to be twice as loud as another when they are about 10 dB apart. Therefore, to the human ear, a chainsaw will sound 32 times as loud as a conversation. However, the sound intensity – which is what really matters when it comes to hearing loss – will be one million times greater.
Long or repeated exposure to sounds at or above 80 dB(A) (twice as loud as a vacuum cleaner) can cause hearing loss. The louder the sound, the less time it takes for hearing loss to happen. NIHL is cumulative, so you’re more likely to experience it if you’re exposed for long periods.
As a simple guide, your workplace might have damaging levels of noise if people have to raise their voice when having a conversation with someone who is about 2m away; employees use noisy power tools or machinery for more than half an hour a day; or noise is intrusive, or worse, for most of the day.
Excessive noise can also interfere with communications, make it harder to hear warnings and make people less aware of their surroundings. These issues can put people at risk of injury or death. Lower levels of noise, such as those in an open plan office, can cause other problems, like affecting your ability to concentrate or causing you to feel stressed.
What your employer should do
The main law dealing with occupational sources of noise is the Control of Noise at Work Regulations 2005. The regulations require all employers to eliminate noise at source or, where that is not possible, reduce it to as low a level as is reasonably practicable.
The regulations also set out three legal noise thresholds:
- the “lower action value” – which is 80 dB(A)
- the “upper action value” – 85 dB(A)
- the “limit value” – 87 dB(A), which takes account of any reduction in exposure provided by hearing protection.
As the name suggests, if noise is found to be at or above either of the action values, then the employer has to take a particular course of action. The limit value must not be exceeded.
If employees’ average exposure to noise is noise is between 80 and 85 dB(A) – the lower and upper action values – then employers must provide them with ear protection if they want it. At this level and above, employers must also give employees information on the risk and what measures can be taken to protect hearing.
Ear protection must be worn if the noise level reaches 85 dB(A) – the upper action value. Employers must mark where is it to be worn and provide staff with training and information on how to use it.
Employers must provide workers with hearing checks if they are likely to be regularly exposed to noise above 85 dB(A), or are at risk for any reason, for example if they already suffer from hearing loss. Health surveillance is vital to detect and respond to early signs of damage.
If an employer suspects that noise exceeds the lower action value, 80 dB(A), they have to carry out a noise risk assessment and plan how to eliminate noise or reduce it as much as possible. In a plan for reducing noise exposure, employers should consider things like:
- Using a different, quieter process or quieter equipment
- Introducing a low-noise purchasing policy for machinery and equipment
- Lining machinery parts with a material that reduces vibration (and hence noise) or impact noises
- Erecting enclosures around machines to reduce the amount of noise emitted
- Positioning noise sources further away from workers
- Limiting the time workers spend in noisy areas
Protection is best achieved by controlling noise at source. Hearing protection, such as ear plugs defenders, is the last resort.
What you can do
- Wear any hearing protection you are provided with
- If you hearing protection seems to be damaged or defective, report it
- If you suspect there may be a problem with noise in your workplace, considering the simple tests above, tell your employer or your safety rep
- You or your safety rep could identify if there is a problem with noise by carrying out a survey with workers that may be affected or using body and risk mapping techniques.