NOISE ASSESSMENT AT WORK
Hearing protection
Can noise-cancelling headphones be used at work
Applies equally to in-ear ‘bud’ style and over-head / over-ear
Whether standard music-playing headphones can be used at work
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It is getting increasingly common to see people wearing noise cancelling music headphones when working in high-noise environments and the question often arises: “Are noise cancelling headphones OK to use as hearing protection at work?”.
The urge to wear them is perfectly understandable as on the surface of it they do reduce the external noise levels and the user can then listen to something all day rather than working in silence, but do noise cancelling headphones also work as hearing protection and can employers permit it?
A problem with music headphones in a high noise area is that it is impossible to tell whether any hearing loss has been caused by the music or the environment. The high noise environment makes it more likely the user will listen at higher volumes to overcome environmental noise and this will damage hearing. The employer can be held liable for those hearing losses as it cannot be proved it was the music and not the workplace noise which caused them.
Offices and other low-noise areas
We are looking specifically at using standard music headphones in a high-noise environment at work; areas where hearing protection is needed. For low-noise areas such as offices, then that is purely down to company policy. If people don’t work in high noise areas then listening to headphones all day could cause hearing damage, but as that damage is not caused by environmental noise at work the employer will not be liable for it. Also, if you are not at work then it’s entirely your choice.
The very short answer
If you have a noise risk in a workplace, then the hearing protection used must be certified to one of the branches of EN352 and as such would have an SNR figure. Standard music headphones, noise-cancelling or not, are not certified to this therefore their use in a high noise area at work is illegal and a company cannot permit their use without breaching their statutory responsibilities. All the rest below is on the practicalities on using noise cancelling headphones at work, but beyond that it is a simple ‘if there is no certified SNR figure for them, they are illegal’.
How loud do people listen to music on headphones?
Typically, users listen to music at around 15dB over the background noise they are experiencing, as a minimum, in areas where there is background noise, realistically, a lot louder. This means that if they are hearing 80dB from the outside, for example at work or in a coffee shop, then they will be playing the music back at least at 93 to 95dB to hear it over that noise, and in all likelihood much louder than that.
(The ‘listening to music at 15dB above background’ thing is a little more nuanced that the bare statement implies. For a start, it is a minimum figure, and it also depends on what mood they are in, what type of background noise the music is trying to drown out - a constant drone or irregular thump will make a difference, etc.).
When background noise levels are quiet, people still tend to play music at higher volumes. I have some ear muffs which also play music but as they are hearing protection first and foremost, they won’t play back at over 85 dB(A) and this seems very quiet. Nobody listens to music at that level normally.
How loud do phones go? That’s a hard one to answer as it can very much depend on the headphones used with them. An iPhone can put out anything from 100 to 110 dB at full tilt, and other brands are similar, so well into danger levels.
Using bone conduction headphones at work in high noise areas
Bone-conduction headphones cannot be used at work in high noise areas. Even if someone wears ear plugs and then uses something like the Aftershock bone conduction headphones, the headphones just add the noise back in which the plugs have taken off, and the upper limit of the noise they can give is well over the 85 dB level where damage starts to be caused. Bone conduction causes exactly the same damage to hearing as normal noise.
Types of noise cancelling headphones
These will either be ‘passive’, i.e. they physically block the noise; or ‘active’, meaning they use electronic magic to cancel out external noises.
How passive noise-cancelling works
Basically they work in the same way as ear plugs. These are usually in-ear ‘bud’ style headphones which go into the ear canals, and normally have a soft silicone seal around them. They physically block noise entering the ear canal and the silicone seal absorbs some of it. Essentially they act like a standard ear plug, except with a built-in speaker.
Passive noise-cancelling / noise isolating headphones can reduce the noise levels by a decent amount, again though, they have no SNR rating so have no certified noise reduction figure and are not the same as ear plugs.
How active noise cancelling works
Sound is a wave, with peaks and troughs, (or to be more accurate, areas where the air is compressed and areas where it is less compressed). Noise cancelling headphones work by having a microphone on the outside which listens to the sound, then it almost instantly plays back the opposite of that sound inside the headphones. That means a ‘peak’ comes in from the outside of the headphones, so the headphone plays a ‘trough’ at the same time, and the two cancel each other out.
What about phones with volume limits?
Higher-end phones have volume limits which can be used to ensure hearing is not damaged. There are a few issues with this:
The phone and headphone must ‘match’, i.e. be from the same manufacturer, otherwise the phone has absolutely no idea what volume the wearer is actually getting. If you have a Samsung phone and Sony ear buds, the phone doesn’t have a clue what volume you are listening to.
Remember, we are talking about being at work, therefore are not talking about an individual who actively wants to minimise noise but someone who has had hearing protection forced upon them. So even if they have say Apple AirPods Pro and an iPhone, they are unlikely to set volume limits, and are more likely to try and over-ride volume limits. The employer has absolutely no control over this.
Volume limits on phones frankly are a bug rather than a feature. In my own work, I wear bluetooth hearing protection which cannot go loud enough to damage hearing, but to hear it you usually have the phone on full whack. Apple start annoying me that I am listening to dangerous volumes when I clearly am not, then the volume gets limited and I can no longer hear anything. So I just reclassify the bluetooth headphones as ‘speakers’, which removes the limiter, and sorted. Anyone with non-matched headphones will do that.
By how much do noise cancelling headphones reduce external noise?
Given the principle that a wearer will listen to the music around 15dB higher than the external noise they are hearing, minimum, the amount they reduce the external noise by heavily influences the volumes the user will play music or podcasts at. The less the headphones reduce the external noise, the higher the minimum volume the user will use to drown the noise out.
No headphones, or indeed earplugs, block out all external noise, that is impossible to do. There are a lot of newer manufacturers getting into hearing protection and often making claims about being ‘able to hear nothing’ or ‘blocks all external sound’. Frankly, absolute bollocks.
Data courtesy of RTings website
'Amount of noise reduction’ is not the same as SNR, these have no rated SNR
What volumes will people be listen to music at with noise cancelling headphones?
From all the noise assessments I do, a typical noise level in a production site is about 95 decibels, give or take. We will assume people will listen to their music at a minimum of 15 dB over the background noise they can hear after the effects of the noise reduction are taken into account, and more realistically up to 30 dB higher.
This means the volume levels they will likely experience are:
As a general rule, you get what you pay for. The Sony XM3 and XM4s, Bose QC35 and Apple AirPods Max are all more pricey, but all come in slightly below that critical 85 dB limit at the minimum level of 15 dB over background noise, whereas all the others exceed it even at this minimum level.
However when cranked up to realistic volumes, noise exposures in all of them will far exceed the safe 85 dB level.
The high risk of hearing damage when using these noise-cancelling headphones in place of hearing protection at work is significant. For example, the AirPods Pro result means the user may be experiencing 102 dB every day if wearing them in a high noise area. At this level they will exceed their daily safe noise dose in around nine minutes.
Summary of using noise-cancelling headphones at work.
There is one factor which over-rides any actual performance data - hearing protection must be certified as such and meet BS EN 352, and carry specific data about how much noise reduction it gives, etc.
None of these music-playing noise-cancelling headphones are certified to EN 352 for hearing protection, therefore none can be used as hearing protection at work.
As they are not certified to EN352, any claims about noise reduction are mainly marketing, they have no certified reduction levels, even Apple’s AprPod Max, hellishly expensive though they are, have no EN352 certified noise reduction figures.
Even if the headphones are capable of reducing the noise levels enough to be safe through active or passive noise cancelling, because they are capable of going well over the 85 dB limit when playing music, all have the potential to cause hearing loss as the user will just add the noise back in. People will still be exceeding the 85 dB(A) limits, just now as a combination of machinery and music.
But there are ways to still have music and hearing protection…
I do noise assessments and understand the desire to listen to something while a day drags on. Standing watching a carpet-threading machine for an hour is so boring it makes you want to end it all, so listening to something like the radio is a big help and there are solutions. There are several types of hearing protector on the market which have features such as DAB radio, FM radio, or Bluetooth connections, and they aren’t necessarily all that expensive.
They differ from regular headphones because they are hearing protection first and foremost, meaning they are certified as such, so for example:
They are certified to EN352
They have a certified SNR
And importantly, they will not go above 85 dB inside the headphone - you cannot turn them up so loud it will damage hearing. You can’t over-ride that limit.
The ones I now use are ISOTunes Link muffs, which have a Bluetooth connection and superb sound quality; they are properly good. ISOTunes have a range of Bluetooth-enabled hearing protection including muffs, corded plugs and cordless plugs. I’ve tried both the plug and muff types and both are excellent - good noise reduction, comfortable and good sound quality.
If you want to listen to music in high noise areas these are a very good way to go.
A suggestion for employers
The urge for employees to wear something allowing music or radio playback is understandable, especially on routine jobs. One route I’ve seen is to make standard plugs and muffs available free of charge so meeting the obligations to provide PPE at no cost. But alongside that, then offer a contributory payment towards ISOTunes hearing protection with the employee paying the rest if they want them. That seems like a reasonable compromise and it can meet them half-way on allowing them to listen to something while still having protection, and as they have paid towards them often increases compliance with the wearing of hearing protection.
Otherwise, look at the costs of your disposable protectors. Often things like the ISOTunes actually work out cheaper per person than a year’s worth of disposable protectors and after that year, you are quids-in.
P.S. Apple, get your AirPods Pro certified to EN352 and the market would be huge…
Links and sources
The superb RTings.com website has extremely good reviews of in-ear and over-ear headphones. Rather than just ‘these sound good’, they stick them in a lab and do loads of tests to get actual performance data on each.
BSI, as ever, don’t make EN 352 available for free, but this website has a decent summary of it and how it applies to hearing protection.
ISOTunes range of Bluetooth-enabled hearing protection
G.P. recommends an individual wears noise cancelling headphones at work
This is a genuine case. A GP wrote to an employer stating that an individual should use noise-cancelling headphones at work as they were suffering from vertigo. The GP in question even specified the Sony XM3 noise cancelling headphones. There are several issues here:
To be clear, GPs are good at medical stuff, but they largely know the square-root of sod-all about hearing protection, noise at work and the regulations around it.
What the GP stated in this case was actually illegal for the employer to do. As the noise cancelling headphones are not certified hearing protection they cannot be used.
GPs are not blessed with all-reaching omnipotence and don’t have the power to make an employer do something illegal.
The GP also seems to have no idea about noise safety as the individual wearing the Sony headphones for eight hours a day every day sooner or later will be back at the GP’s complaining of hearing loss.
The outcomes are more complex. If there is a genuine medical issue which prevents someone wearing hearing protection then that would mean they cannot work in a high noise area. The employer should then provide them with an alternative position in an area of lower noise where hearing protection is not needed.
If a lower noise position is not available then the employer still cannot permit them to work in the higher noise area without hearing protection, so the only option is dismissal. Not great for the employee, not great for the employer, but the situation is forced up on them by the medical issue which prevents hearing protection being used.