How can we recapture the silence?

Silence is valuable and rare, according to our author, Klaus Esterluss. He asks how we can reduce man-made noise and its impact on humans and animals. One thing is clear: It will require compromise.

As I look out from my vantage point on a hill, a meadow spreads out around me and bare trees awaiting their first leaves grow in the distance. Birds land on the branches and welcome the newly arrived spring season with their song. A stream babbles through the woodland.

Nature and Environment | 20.04.2018

Although the last few houses of the nearby village are just a few meters away, I hear nothing but the sound of nature.

Then a muffled droning rises up from nowhere. I look around and eventually discover a plane streaking across the sky. I'm irritated but at the same time, I wonder why. In Berlin, the noise would barely register with me. It would disappear in the cacophony of the city or behind my headphones. 

Our perception of noise depends a lot on the context. In the countryside, the noise from a plane might be annoying, in the city you might not even notice it.

But out here, in the Thuringian countryside, things are different. If I put on my headphones, I'll block out the sound of singing birds, babbling brooks and rustling wind. I decide in favor of the birds and put up with the airplane.

Nature and Environment | 27.03.2018

Must we just live with the noise?

Over the past few weeks, I've learned a lot about noise. I've spoken to a researcher who experiences natural environments free of man-made sounds every day. I've learned that noise on land and underwater are very different things. Perhaps most importantly, I've learned that such noise can pose a problem for humans and animals alike.

Back in Berlin, I begin to question whether we have to put up with a world that is so loud? What methods are available to bring a little quiet into our lives and to protect people and animals on land and underwater? 

Good planning equals quieter cities

Engineer Thomas Preuß spends his days at the German Institute of Urban Affairs (DIFU) figuring out man-made noise and how to ameliorate it.  Clever urban planning and building measures can play a major part in the solution.

More bicycles and less cars in the city: reducing noise will require compromise

"Road traffic is definitely the most significant source of noise in cities," he says. But construction work, industry, sporting venues and bars and restaurants all contribute something to the din in the city too.

In principle, one can differentiate between temporary noise, like my plane in the countryside, and constant noise.  "Active noise reduction," measures can help against the latter, says the researcher. 

"One has to try to reduce the amount of traffic. That means allowing fewer cars in the city or reducing speed limits," says Preuß. The art of urban planning is really about winning back parts of the city as a recreational space for everyone. 

But that can't happen without compromise. "For instance, if you want to promote cycling, then you inevitably have to force back car traffic. You can't have one without limiting the other," Preuß told DW.

Underwater drive-throughs

The same goes for underwater habitats. Still, there's an important difference. Noise travels faster and further in bodies of water. Up on solid ground, the racket on a building site will only be heard by the unfortunate people nearby. But for animals under the sea, in lakes and rivers, that din would be heard over many kilometers, according to Alexander Liebschner from the German Federal Agency for Nature Conservation (BfN).

To find solutions here, we have to turn to those responsible for creating the noise in the first place, such as construction companies building offshore wind parks, the foundations of which have to be anchored in the seafloor using heavy machinery.  Universally adhered to rules and upper limits are required to tackle this kind of racket, say experts.

The construction of offshore wind parks and motor boats are among the big sources of noise pollution in the ocean.

In Germany, such regulations already exist to protect porpoises in the North Sea, says Liebschner. That's largely because government ministries worked with offshore wind companies, conservation organizations and coastal federal states to find a solution.

Industries that work underwater are also developing innovative technologies to curb noise pollution, added Liebschner.

But it's not just industries working underwater who are behind the commotion. Motor boats can pose problems too. Andy Radford from the University of Bristol is researching their impact on the Great Barrier Reef ecosystem and is trying to find realistic solutions to the dangers.

Radford doesn't believe a blanket ban on boats in marine protected areas is plausible. "But what is happening is that you can redesign motorboat engines to be quieter," he says.

A switch from two-stroke to four-stroke engines appears to make a difference, says Radford, who references the results from newly published studies.  He also recommends protecting particularly sensitive areas, such as spawning grounds, at particular times of the year, in an attempt to reduce noise.

Switching off the noise

After conducting many interviews, I get the impression that successfully reducing noise has a lot to do with finding compromises and that won't happen overnight. Studies have to be carried out and evaluated, and regulations created, implemented and monitored on a regional and global scale.

The good news is that if we manage to come to a compromise, the racket would disappear relatively quickly.

"If you take chemical pollution for example, chemicals linger in the ocean for a very long time, even if you were to somehow stop the source", sagt Andy Radford. "If you turn off a noise source or you move it further away then it's current effect immediately stops." When it comes to noise pollution, there is no echo that continues for weeks, months or decades.

That also applies to Berlin and my little hill in the countryside. The plane and its droning disappear after a few minutes. Just the singing birds, the flowing stream and the rustling trees remain.

Don't shout like that, I'm not deaf.

The vacuum cleaner

Let's start with something small and seemingly inconspicuous. The common coqui is a Costa Rican frog with a reputation for being a bit of a loud mouth. Though measuring a diminutive 4 cm, these nocturnal amphibians make their mark by bellowing at volumes of 70-plus decibels. That's the same volume as seriously loud music and prolonged exposure can lead to hearing problems.

Don't shout like that, I'm not deaf.

Just like a subway

Second on this list is the water boatmen, a tiny aquatic insect who has an unusual and rowdy way of attracting a mate. In rubbing its penis on its tummy, it creates noise as loud as an underground train, a little over 100 decibels. But because the sound is emitted underwater, our landlubbing ears are preserved.

Don't shout like that, I'm not deaf.

Slightly quieter than thunder

Anyone inclined to stand five meters from an elephant might be well advised to cover their ears. Keen to be heard at great distances, the mammals trumpet at volumes of up to 103 decibels. Why five meters, you ask? Easy. That's the distance at which the volume was measured. And it's about as loud as a pneumatic drill.

Don't shout like that, I'm not deaf.

The drum set

The African cicada has achieved noise notoriety. The loudest well-known insect, it uses its tympanal organs to "sing" at volumes averaging 106.7 decibels. By comparison, the average human voice just about struggles into the meager 60 db range.

Don't shout like that, I'm not deaf.

Like a chainsaw

There is something terrifying about a lion's roar. In part, no doubt because as hungry carnivores with sharp teeth and strong jaws, they can pose an existential threat. And though the king of the animals can make a ferocious sound with apparent ease, it is not the loudest in the kingdom. Not at a mere 110 decibels.

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Don't shout like that, I'm not deaf.

Louder than a jackhammer

The howler monkey's name precedes it. Able to scale towering trees and sound heights of 128 decibels, these native South and Central American animals are louder than ambulance sirens and can be heard from several kilometers away.

Don't shout like that, I'm not deaf.

Similar to a car race

The kakapo or night parrot is reputedly the loudest bird in the world. Possibly by means of compensation for the fact that it can't fly. The male has been heard screeching for a mate at a heady 132 decibels. At night, of all times, which is when these tubby herbivores are most active. And let's face it, who wants to sleep next to a creature that's louder than the average human pain threshold?

Don't shout like that, I'm not deaf.

Just like a rocket launch

When the Panamanian sky fills with greater bulldog bats, it also fills with noise. They've been recorded making a 140 decibel din, but given its high frequency (55kHz), it is inaudible to the human ear. Which is lucky since volumes of 120 db pose a threat to our hearing.

Don't shout like that, I'm not deaf.

Launch of the Saturn V rocket

The second to last animal on the list emits a very loud, if short-lived bang into the world. Snapping or pistol shrimp can hit a raucous 200 decibels, which are dampened by the water in which the sound occurs. But even after subtracting the rule of thumb 60 db to calculate the air level, it makes the little crustacean extremely loud.

Don't shout like that, I'm not deaf.

Basically an earthquake

Even louder, however, is the sperm whale (going on latest research at least). These ocean giants who can grow to be 20 meters long and 50 meters in weight, are impossibly loud. Scientists have measured sounds of up to 230 decibels, which is a good bit louder than a jet.

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