Sounding off about noise pollution
Whenever I open a newspaper or click on a current affairs website, one thing becomes immediately clear: the modern world faces a number of existential threats which, if unchecked, threaten to derail our civilization and so, rightly, capture most media attention.
Yet to narrow our gaze to these core perils is to ignore the myriad other issues that jeopardize our modern post-industrial age quality of life, albeit, perhaps, in a less dramatic fashion.
Take noise pollution. Even among the fraternity of ‘pollutions’ plaguing our planet, noise pollution might initially appear a minor inconvenience compared to rising CO2 levels, plastic pollution or struggling water systems. But, to label noise pollution as unimportant is to ignore a troubling array of data.
Think no one ever died from noise pollution? That would be a tragic misconception. In Europe alone, long-term exposure to environmental noise is believed to cause 12,000 premature deaths annually and contributes 48,000 new cases of ischemic (arterial blockage) heart disease per year.
Clearly, this is a public health hazard which warrants deeper investigation. The first step on the journey entails defining exactly what noise pollution means.
Only then can we strategize how to turn down the volume on this often-overlooked enemy to the experience of being alive.
Wrong sound, wrong place, wrong time
From a psychological perspective, noise exists purely as a subjective experience.
As the United Nations Environment Programme (UNEP) notes in its Frontiers 2022 report on environmental issues and solutions: “When sounds are unwanted, they become noise. When noises are too loud and persist too long, they become noise pollution.”
Bu first, let us put aside the myth that ‘silence’ is some magical panacea.
Silence is, after all, pure myth.
Neuroscientists have shown that even in environments without external noise, the human brain is sensitive enough to detect the sound of air molecules vibrating inside ear canals, or the swish of fluids in the ears themselves. And the only reason we aren’t continually distracted by the thumpity-thump of our own heartbeats is because the insular cortex filters sensations between heart and brain – maintaining that critical distinction between internal and external stimuli.
Without any conscious action on our parts, most of the distracting background noises in our daily lives are filtered out, leaving us free to concentrate on the events – or sounds – that require our real attention.
Modern noise pollution confounds these millennia-old brain filters. Think of noise pollution as the wrong sound, at the wrong time, in the wrong place or at the wrong volume. And it’s everywhere.
Cars roar down the road. Planes drone through the sky. Trains hurtle along rattly lines. Heavy machinery clanks and clangs at factories, building sites, and intersections. Sound leaks into the day and night from sports arenas and concert stadiums. And let’s not forget the constant tapping, beeping, chiming and whooshing sounds of everyone around you on their phones!
Amid this maelstrom of competing soundwaves, we live, work, contemplate and, if we are lucky . . . sleep.
Although the latter might just depend on where we call home.
The noisiest places on Earth
Over half the world’s population live in cities. A trend which is expected to continue, with the urban population predicted to more than double by 2050. Yet a city is a nexus of noise. The World Health Organization (WHO) recommends average road noise limits of no more than 53 dB on any given day. But the actual statistics for road noise come through loud and clear.
In Asia, Dhaka, capital of Bangladesh, records road noise levels up to 119 dB. Moradabad, India, hits 114 dB. Islamabad, Pakistan, reaches 105 dB. parts of Ho Chi Minh City, Vietnam, can grow as loud as 103 dB.
In Africa, Ibadan, Nigeria, reaches 101 dB, with Algiers, Algeria, not far behind at 100 dB.
Cities in the Western world, while not matching these cacophonous highs, still experience traffic volumes way in excess of recommended levels.
New York, USA, hits 95 dB; Puerto Vallarta, Mexico, 85 dB; and Bogota, Colombia, 83 dB. Across the Atlantic, London, UK, reaches 86 dB; Tokat, Turkey, 82 dB and Paris, France, 89 dB.
One of the most obvious manifestations of extreme noise pollution is an increase in cases of hearing loss.
Of the approximately four million people in the USA with hearing loss, about 25% of cases are deemed ‘noise induced’. This is perhaps unsurprising, given that around 30 million Americans are exposed to hazardous decibel levels in their places of work every day.
One recent study found that people living in cities have hearing ages 10 to 20 years older than their actual ages – evidence of the tangible link between urban noise and damage to the human auditory system.
Of course, it’s not just the auditory system that suffers due to the impact of excess noise. Noise pollution affects the whole body and, beyond that, the human mind – often with devastating consequences.
Noise takes toll on body and mind
Ongoing exposure to noise pollution has been shown to cause a range of symptoms, from annoyance and sleep disturbance, all the way up to cardiovascular and metabolic disease, and even cognitive impairment.
Two case studies reported on by the UN demonstrate how the psychological disturbance of noise can emerge as serious physical ailments. In one, a synthesis of noise data and medical data in South Korea showed that instances of cardio- and cerebrovascular diseases rose by 0.17% to 0.66% for every 1 dB increase in daytime noise. In another, residents of Toronto, Canada, exposed to elevated traffic noise were found to have a higher incidence of heart attacks and heart failure. Risk of diabetes and hypertension also increased.
Nighttime noise pollution is especially pernicious. Disrupted sleep patterns interfere with the body’s hormonal regulation and cardiovascular functioning, causing both physiological and psychological stress responses.
Nighttime noise is the primary reason why, by some estimates, 22 million people in Europe suffer from chronic noise annoyance, and 6.5 million suffer from sleep disturbance. Across the EU, around one-in-five people are regularly exposed to noise levels categorized as harmful to health.
Excess noise targets mind as well as body. Researchers at America’s National Centre for Biotechnology Information (NCBI) have discovered a strong correlation between noise pollution and depression. ‘Strong noise annoyance’, they found, was associated with a two-fold increase in depression and anxiety in the general population.
The very young and the elderly are two particular at-risk groups. So too are the impoverished, with poor families often compelled to live near typically noisier locations, such as industrial zones, busy roads, or waste dumps.
Pregnancy also increases vulnerability. One 2018 study found expectant mothers exposed to higher levels of noise pollution were more likely to develop preeclampsia, a dangerous condition causing high blood pressure.
The ripples of noise pollution even stretch into the developing mind. Some 12,500 schoolchildren across Europe are believed to experience reading impairment specifically due to aircraft noise. Children living near airports have even been shown to exhibit signs of long-term memory loss.
It’s not just human life that suffers – so too do the creatures with whom we share our biosphere.
Anthropogenic noise pollution frequently emerges at sub-4kHz frequencies, overlapping with frequencies used for animal communication and foraging. Bats, for instance, use echolocation to hunt prey, but background noise means they must fly longer distances to find sustenance.
Creatures rely on acoustics for a range of other essential tasks, from attracting mates to protecting territory and warning of danger. Deprived of these fundamental abilities, everything from birds in the sky, to insects and amphibians living alongside freeways, face premature deaths and fewer opportunities to reproduce.
Living beneath the sea is no protection. The confusion of noise from boat engines, sonar sensors and deep-sea mining equipment hampers the ability of sea life to navigate and communicate. Large container vessels can emit noise at 190 decibels, cutting nearby echolocation ranges by up to 95%. In North Pacific waters off the Canadian coast, orca numbers are in freefall and salmon numbers have plunged by 60% over the last four decades.
Noise pollution even affects food production. If pollinators such as bees, beetles, butterflies and moths abandon an area due to excess noise then plant life deteriorates – extending the issue of noise pollution right to the heart of our farming and cultivation systems.
Noise pollution is the secret enemy in our midst. It doesn’t even bother to keep a low profile. Daily it vrooms, roars and buzzes in our eardrums – yet somehow still passes beneath the radar.
While the world’s greatest minds conspire to counter the threats of air and water pollution, noise slips silently off the agenda. Somehow, we must turn the tables on unwanted noise to help restore our quality of life.
Creating a more sympathetic soundscape
It turns out there are lots of steps we can take to combat noise pollution – all it takes is the right mix of innovation, willpower and investment.
With the perils of noise pollution becoming ever more acute, urban planners are under new pressure to create more harmonious soundscapes. Indeed, soundscape design is swiftly becoming a discipline of its own, dictated by a landscape’s natural features, its pre-existing infrastructure and intended public use.
What’s more, some of these methods dovetail neatly with efforts to make our environment cleaner, greener and more visually pleasing.
Trees, for example, when planted at sufficient density, act as an excellent sound buffer by roadsides, soaking up the noise of traffic before it reaches residential zones. Shrubs, vegetated walls and roof gardens similarly absorb acoustic energy and reduce the amplification of sounds compared to solid, urban surfaces. Not to mention the CO2 sink they provide.
The impact is significant. “Customized placement of tree rows behind traditional highway noise barriers or layers of vegetation on rigid noise walls can reduce noise levels by up to 12 dB,” UNEP notes in its Frontiers 2022 report on noise pollution.
When all else fails, solutions can be engineered. Consider the different types of barriers that can be erected to separate the sources of noise from innocent residents and passersby. Earth berms (raised shelves of compacted soil) and gabions (cages filled with earth or rocks) make excellent, long-lasting and inexpensive barriers. Recycled products such as plastic and car tires have proved particularly effective materials for acoustic shields. Even fiberglass from decommissioned wind turbine blades has been shown to cut traffic noise levels by 6-7 dB.
Still, rather than buffering our public and private spaces against unwelcome noise, what about tackling the problem from the other angle – reducing the amount of noise we create in the first place?
Turning down the volume on noise pollution
What about the roads themselves? Recall that infernal ‘roar’ of friction as rubber tires roll along the highway. Surely there must be something we can do about that modern day curse?
According to science, less speed equals less energy converted to sound. So, as a rapid low-cost remedy, byelaws can be implemented at local level to cut speed limits and reduce noise levels – and increase safety – accordingly.
From a technological perspective, the steady takeover of electric vehicles (EVs) will gradually reduce the burden of traffic noise. EVs are typically 4-5 dB less noisy at low urban speeds than comparable ICE models.
At higher speeds, it turns out that new road materials such as porous asphalt surfaces help lower noise emissions too.
Technology can also help stifle noise pollution from railways. TATA Steel, for example, has begun installing its SilentTrack lines on rail networks.
TATA manufactures special dampers (made by encasing steel in a rubber-like material) to absorb track vibrations, potentially reducing noise output by up to 50%.
From the rails to the skies. Noise pollution from aircraft can be reduced by ongoing improvements to aerodynamics and components for aircraft. Flight paths, meanwhile, can be directed away from population centers. Community engagement is a must, though. Public consultations should be mandatory before any introducing any changes to flight regimes near urban areas.
In buildings prone to major noise emissions, such as factories and industrial units, special acoustic insulation can help shield the outside world from sounds originating within. Grants could be made available to help industries replace ageing machinery with newer, quieter upgrades. Due to increased efficiency, this modern machinery is also likely to consume less energy and emit fewer pollutants.
Worldwide, legislators and lawmakers can work together to reduce the demand for noise-creating activities altogether.
Expanding a national network of cycle lanes will help cut reliance on private vehicles; so too will introducing more car-free zones in residential sectors. Pedestrianizing city centers has a similar effect. In an ideal world, our busiest streets would echo with nothing more than the sound of footfalls.
Cycle hire schemes likewise encourage people to swap four wheels for two. Take New York’s Citi Bike scheme, for instance, with 25,000 bikes and more than 1,500 stations across Manhattan, Brooklyn, Queens and beyond.
London’s Ultra-Low Emission Zone, launched in 2019, played its part in noise reduction by financially incentivizing the adoption of quieter hybrid and electric vehicles. Under the new rules, a £12.50 daily charge is applied to vehicles failing to meet European emission standards. The scheme is estimated to cover an area of land populated by some 3.8 million people – and by August 2023 will be expanded to include the whole of Greater London. 
In Berlin, where more than half a million people were routinely exposed to noise levels exceeding the 53 dB recommended limit, many two-lane roads were reduced to single lanes – leading to an immediate drop in nighttime noise levels for some 50,000 residents.
At an international level, the EU’s Environmental Noise Directive promotes the monitoring and reduction of noise pollution across the community. It compels countries to produce noise maps and action plans every five years for all cities of more than 100,000 inhabitants and all roads carrying 3,000,000+ vehicles annually.
Sometimes, of course, the most effective remedy to noise pollution is . . . escape.
The mental health benefits of natural sounds and quiet sanctuaries are now well established. Green spaces (parks, public gardens, canal towpaths, nature reserves and leisure areas) generate positive psychological effects by providing respite from the antagonizing commotion and babel of modern urban centers. These places will not develop or protect themselves. They will need sanctioning, funding, and ongoing support at neighborhood all the way up to regional level. Commercial interests alone cannot be allowed to govern our access to nature, to cleaner air, and to peace and quiet.
It stands to reason that the more green spaces our societies accommodate, the more balanced we will all feel within the modern world.
Sounds like a plan?
We have acknowledged the dangers of noise pollution, which can go beyond annoyance to actually threatening life and health. Now together we must strive for a more acoustically attuned world.
This effort will encompass all strata of society: from lawmakers drafting policy; to urban planners and architects hunched over blueprints; to captains of industry controlling the factories, technologies and machinery that will shape our future.
But the issue of noise pollution also falls to us, as individuals. Which vehicle should I buy? Shall I use public transport to get to work? Should we take that extra foreign holiday this year? What are the priorities of the political party I vote for?
All of these decisions and more will dictate the amount of noise our towns and cities generate in the years and decades to come – and the extent to which ‘peace on Earth’ takes on a whole new meaning.