Emma Shanks, Noise and Vibration Specialist at HSE’s Laboratory, explains the importance of looking after our hearing both in and outside the workplace – particularly when lives may depend on it.
Picture the scene: you’re at a large family gathering for a special occasion in a busy pub. You’re attempting to tell Aunt Sue (who, to be fair, is getting on a bit) all about Jack’s school award; but you’re struggling to hear and make yourself heard…
Now picture a different scene: this time it’s the site of a major incident requiring the attendance of all the emergency services; there’s lots of vehicle and machinery noise, lots of communications traffic – and one vital instruction you absolutely must hear, but miss…
OK, so these scenarios may be imaginary, but the sound environment in each is very real. In the pub, the reflective surfaces, background music and other people’s conversation all add up to create a din.
Aunt Sue can’t hear you properly so you move in a bit closer, raise your voice and repeat yourself; although this time you use slightly different words. People around you speak even more loudly to be heard over you, raising the noise level over your repeated message. Oh, and you didn’t repeat exactly what you said before – you used different words. It’s no wonder that Aunt Sue’s very confused.
At the ‘major incident’ this ever increasing sound environment could mean the difference between hearing an instruction or alarm, and not hearing it – with potentially disastrous consequences.
Oi! Keep the noise down!
The sound environment is made up of ‘wanted’ and ‘unwanted’ sound (aka noise). At our ‘major incident’, instructions, commands and essential communications are wanted sound, whereas engines and (in some cases) sirens could be described as noise.
Long term exposure to noise can lead to hearing loss. And hearing loss brings challenges including, but not limited to, the inability to carry out work, impaired communication, and social isolation. In turn, these challenges can lead to stress, anxiety and depression.
There is no magic way of completely separating noise from wanted sound. But there are ways of managing noise, controlling people’s exposure to noise and ensuring continued hearing health for workers.
We’re naturally capable of noise risk management
Loud and intrusive noise is a potential risk to hearing and communications. But in everyday life we often instinctively manage noise risk without even realising it; we just don’t normally call it noise risk management.
Let’s return to our family gathering in the pub (it’s your round).
To properly tell Aunt Sue about Jimmy’s school award you might choose to find a quieter location where you can talk and be heard normally, away from the pub din. The same idea applies equally to the ‘major incident’: would you hold a critical discussion right in the middle of all the noise? Probably not; you would move to a comparatively quieter location.
Noise risk management and hearing conservation is about anticipating the risks, then putting actions and controls in place to avoid those risks before harm is done. It’s not simply a case of popping hearing protection on everyone.
In the pub and at the ‘major incident’ the conversation was moved to a quieter location; an example of risk elimination through process change.
If PPE is required, it must be appropriate
Personal Protective Equipment (PPE), in this case for hearing protection, should be considered the last line of defence. Worn to reduce the level of harmful noise reaching the ears, hearing protection can bring its own set of challenges to a situation. It can make alarms and other safety signals harder to hear. It can also reduce the audibility of essential communications. Correct selection for the intended use is important, rather than selecting the cheapest protector, or the one with the biggest attenuation number. The choice of hearing protection is wide and can include additional features such as audio communication, sound restoration and active noise reduction.
Sometimes, an item of PPE needs to ensure sound is clearly heard rather than reduced. One example is the police public order helmet. Noise attenuation is not right at the top of the list of ‘things that are important in a public order helmet’, but these helmets must allow the wearer to maintain awareness of their environment and hear communications. That’s why the helmets have little mesh holes around the ears.
When the alarm sounds…
Being able to clearly hear and understand speech, warnings and alarms is essential, particularly if they are unexpected. There are standards that define audibility in terms of how loud these kinds of signals should be, relative to the noise environment. In the pub, think about the fire alarm going off. You wouldn’t necessarily anticipate that it was going to go off, but if it does sound, you want to hear it clearly, distinctly, and understand that it requires your attention and action. You also need to clearly hear any instructions from the staff.
Similarly, at the ‘major incident’, in amongst all the hubbub and action, emergency services personnel want to clearly distinguish the sounds that require their immediate attention; for example, the outputs from distress signal units (DSU). But remember that just being able to hear these devices is not sufficient; they need to be loud enough over any background noise to attract attention. For radio speech communications, using the most appropriate equipment is vital – ensuring it doesn’t mask any non-radio communications.
Look after your hearing during leisure time too
Employees of all ages should be encouraged to look after their hearing, even if they already have some hearing loss. This means being aware of the potential effects of leisure pursuits as well as any noise exposure due to work; for example, clay pigeon shooting or nightclub DJ-ing are both likely to expose you to potentially harmful noise. You may notice some temporary tinnitus (ringing or humming in the ears), or changes in your ability to hear the radio, television, or conversations in the pub. Remember: you don’t take your work ears off and put your home ears on!
The more formal approach to looking after hearing health is through health surveillance provided by your employer. This usually involves a health questionnaire, a visual check of your ears and an audiological hearing assessment. There have been recent developments exploring the potential of a new LIDEN approach (Leading Indicator of Damaging Exposure to Noise) which uses otoacoustic emissions (OAEs) to detect early effects of noise exposure on your hearing mechanism, before you even notice it’s happening.
Whilst such developments are encouraging, when it comes to looking after your hearing, as with most health and safety issues, prevention is better than a cure.
You hear what I’m saying?
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