Are your power tools giving you diabetes? Is the racket you live with affecting the value of your home? The level of noise around us is a ticking health time bomb – but will anyone be able to hear it? Paul Little explains.
Construction sites, roadworks, home renovations, espresso machines - the world is noisier than ever, or at least, it sounds that way. Of course, you may not have noticed any of those irritants because you're going through life plugged into a device that feeds you a constant stream of music at levels that may not be deafening but are almost certainly doing you harm.
There are two types of health problems associated with hearing: The first is hearing loss itself; the second is a set of disorders caused by noise, which can range from heart disease to diabetes and other stress-related conditions.
Is hearing loss just a function of age, or is society really getting noisier and making it worse? It's hard to say, according to David Welch, head of the Audiology Section at the University of Auckland, because of the way hearing works.
"The problem is that people develop hearing loss naturally and noise exposure accelerates that, but you can't easily tell the difference."
He points out, however, that hearing-related ACC claims had been increasing until "the government changed the law so people had to have more noise-induced hearing loss before they could claim. Rather than resolving the problem, there was a switch to a financial strategy."
He's talking about changes in 2010 - ACC's contribution toward the cost of hearing aids is now based on the proportion of hearing loss which is injury-related.
The number of new claims accepted dropped from 7315 in 2010 to 3449 in 2011.
But further changes in 2014 – primarily ACC covering a consultation allowance and the full cost of having a hearing aid fitted – reversed the situation and there was an increase in new claims with 6081 last year.
So far this year, 5131 claims have been covered.
To have ACC cover for hearing loss, you need to have either lost hearing gradually at work - due to being constantly exposed to noisy work environments - or as a result of a treatment injury, or as the result of a trauma that leaves you deafened, like a blow to the head, or exposure to a single noise event like an explosion, an ACC spokesman says.
"People whose hearing is damaged through, for example, just listening to music too loudly through headphones will generally not be eligible for cover."
Research here matches World Health Organisation studies that show about one sixth of hearing loss is caused by excessive noise.
"Dangerous noise exposure is completely avoidable," says Welch. We've only ourselves to blame if we don't avoid it.
"On the one hand our economy is moving away from manufacturing to office-based jobs, where you're less likely to get noise exposure. However, we are exposing ourselves to more noise, especially though amplified music at other times."
Welch says your smart phone "can easily produce sound levels of 100 decibels or more, which is the sort of level that will start to cause damage to hearing after a few minutes".
Wyatt Page is Associate Professor of acoustics and human health in the School of Health Sciences at Massey University. He observes that increased traffic and housing density have indeed made our world louder, one in which "noise levels at short distances from expressways are well above what would be deemed reasonable".
Although we have standards governing environmental noise that are consistent with World Health Organisation guidelines, they "only get implemented by district plans. Currently we've got, I think, 67 territorial authorities and they all measure noise differently and they don't all use the best version of the standards."
He says that, in particular, listening to music too loud and for too long is a serious public health issue.
"We have here a School of Music and Creative Media Production," says Page.
"I'm regularly talking to them about sound levels in live performance. I tell them that if I applied occupational criteria to what they think is reasonable, they'd exceed a 100 per cent dose in four minutes."
Page is certain that at least some of the health effects of noise are getting worse.
"A good colleague of mine was an audiologist at Wellington hospital," says Page.
"When he started he thought he'd be out of a job soon. But, thanks initially to iPods and now smartphones, it's very common for people in their 40s to be having hearing aids, when previously they would have got them in their 60s."
It's not just our hearing that suffers from high volumes. Environmental noise could be driving you, if not crazy, at least to the cardiac ward. And it doesn't even need to be that loud.
"It is also about how intrusive noise is on people's lives," says Welch, "and how it can stress people so that their cardiovascular health is impacted or how it interferes with their sleep, which also has health consequences."
It's very subjective. "People doing things where there's enjoyment associated have a different view as to what is damaging or loud," says Peter Thorne of the Deafness Research Foundation.
"People who are enjoying themselves in a nightclub put up with much louder sound, but if you were trying to concentrate it would become an irritant."
This is passive exposure – the noise that you can't get away from.
"One man's noise is another man's music," says Welch.
"We've done work around aeroplanes and cars - when people live near a motorway or airport they get exposed to ongoing noise. There's work from around the world showing this has a major effect on cardiovascular health."
Blame evolution. Hearing developed partly as a warning system, hearing is wired to the parts of the brain that are responsive to fear and danger.
"That's why our skin can creep when we hear a spooky sound," says Welch, "or if you are home alone and hear a tiny sound where there shouldn't be one, you can be really freaked out."
That will make you stressed, "which will affect your autonomic nervous system, including the vagus nerve, which controls your heart rate. Our vagal tone keeps our heart rate under control, but when you're stressed that tone diminishes. The heart beats faster, which isn't good for it, and over the years you will start to get a weaker cardio-vascular system."
Another crucial link between noise and health is what goes on when we sleep. Even noises that don't wake us up can affect the quality of our sleep by interrupting the deep periods of rest that are essential to our wellbeing.
Page leads the "Noise and its Effects on People" research platform at Massey's College of Health. In his hierarchy of the non-auditory effects of noise, "the top one is sleep disturbance by a huge margin, then an interesting category called annoyance, then heart and cardio-vascular related diseases, overweight, and even diabetes – because noise increases your stress and they are stress-related conditions."
The problems can start young. "If you were a child going to a primary school and your school was near a busy motorway, then you'd see cognitive development delay," Page says.
He laments that there are no criteria specifically for children, young children in particular. The default is to use the adult criteria.
"We have dropped the ball on this. For very young children, nought to three, exposure should be much lower than adult criteria."
It's possible to get stuck in a loop of hearing problems.
"If you're healthy you can adapt better to noise, but as soon as you get unwell, the ability to adapt or block out unwanted sound is significantly diminished," says Page.
And it gets worse with age.
"Cafe noise is a really good example: it's a combination of your hearing not being as good and the additional cognitive load to tune out the sounds you don't want to hear and listen to the ones you do. That results in increased stress, and a lot of people don't adapt, leading to social exclusion."
Look around at any concert today and a goodly number of the attendees – especially anyone 30 or under – will be wearing ear plugs.
This seems paradoxical: why not just get the band to turn it down? Because it has to be loud to be enjoyed, and that doesn't just mean the volume.
"One reason people like music loud is that you can physically feel it in your gut, your viscera," says Welch.
"Especially the bass, so it's good for dancing - there is a logic to it."
But he sounds a warning about earplugs: "The danger is that people think they're protected when they're not. Putting them in properly is super-important. When you just give people ear plugs at the door, they'll put them in but not very well."
"If you're going to concerts and can't avoid nightclubs," says Thorne,"wearing protection is really important. There are good ear plugs that can be fitted and won't impair the quality of the sound. You can buy them from work safety places or go to an audiologist and get custom-made ear plugs."
He also advises using protection when, for example, using power tools, whether you think they are noisy or not.
There is a lot more we can do to reduce our risk of hearing loss and associated complaints.
First, turn it down, even if that's getting harder.
"There is good work showing the levels people will listen to on earbuds is much higher than they would through a conventional set of speakers," says Page.
"People need retraining to be aware of the dangers of noise."
Page cites the 60-60 rule, which says you should have the volume on your personal media player at no more than 60 per cent of capacity and have a significant break every 60 minutes.
He also emphasises the value of quietness: there are good studies showing that if you live in a quiet neighbourhood your house price is higher and you have better health, even after adjusting for all the common determinants of health.
"There are some efforts to look at limiting exposure on devices," says Thorne.
"The World Health Organisation is producing an app you can play the music through and get information about the dose you're getting."
He would like people to understand that "hearing is a special sense. What you have is what you're born with. If you damage it, it doesn't come back."
He notes that people use more protection with the likes of power tools than they once did and that manufacturers of, for instance, lawn mowers are trying to make them quieter. He thinks any such noisy item should be sold along with its protection.
Welch also says just as he's very happy to pay to have his eyes checked and find there is nothing wrong, the same should go for hearing. He advocates having it checked when young to set a benchmark and regularly after that so any change will be identified quickly.
There's no alternative, so we have got to look after our hearing, because, as Welch says "it keeps us connected with the world".
Stick it in your ear
"These hearing aids are terrible - I can't be bothered with them."
The age-old cry of the deaf relative who irritates their family by refusing to wear their hearing aids turns out to be a perfectly reasonable reaction.
"I use the analogy of a pair of crutches," says Welch.
"If you've lost a leg they help quite a bit – but it's not the same as having the leg."
Hearing aids, alas, don't work like prescription lenses. If you have poor vision and get glasses you will see what you would if your sight was good. But hearing aids work by increasing the level of sound.
"If your ear is damaged in the first place, the hearing aid is still having to use the damaged system to get the information to the brain. They're quite good for what they are. But they are just an electronic gadget. The issue is they still use a damaged organ."