How urban soundscapes affect humans and wildlife — and what may have changed in the hush of lockdown


Kurt Iveson, University of Sydney and Dieter Hochuli, University of SydneyThe dull roar of traffic, the barking of dogs in backyards and the screeching of cockatoos at dusk. The shattering of early morning quiet by the first plane overhead or the garbage truck on its rounds. The squealed delights and occasional fights of a children’s playground.

These sounds and many more create what Canadian composer R Murray Schafer famously called a “soundscape”. Schafer, who passed away last month, helped us realise we experience cities with our ears as well as our eyes.

In recent years, studies have confirmed these soundscapes affect the well-being of urban inhabitants — both human and non-human. But with much of the country back under lockdown, urban soundscapes have changed, sometimes bringing delight, but sometimes causing new distress.

So let’s take a moment to consider how soundscapes influence our lives, and the lives of urban wildlife.

When sounds become ‘noise’

Whether it’s housemates, traffic, or construction, we tend to respond to many urban sounds by defining them as “noise”, and try to shut them out. We do this using a range of techniques and technologies: building regulations on soundproofing, controls on the times for certain activities like construction, and planning measures.

But noise mapping efforts show such regulations tend to produce uneven urban soundscapes — some people are more exposed to loud or annoying sounds than others.

Housing quality is a major factor here, and noise problems are likely exacerbated under lockdown. A recent study of pandemic housing inequality in Sydney found increased exposure to noise during lockdown is significantly contributing to poor well-being.

For example, sounds travelling across internal and external walls of apartments were frequently a source of tension in pre-pandemic times. Now, with so many more people spending more time at home, these domestic sounds inevitably increase.




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It’s not just humans whose lives are disrupted by city noise, as many animals use sound to communicate.

The ever-vigilant New Holland honeyeaters of Australian cities use their alarm calls to warn their friends and neighbours of danger, while the iconic chorus of banjo frogs in wetlands are the hopeful calls of males seeking mates.

This is the sound a banjo frog makes.

Noisy environments can dramatically change how these animals behave. In some cases, animals adapt to their noisy environment. Some frogs, for example, overcome traffic noise disrupting their sex lives by calling at a higher pitch. Likewise, populations of bow-winged grasshoppers in Germany exposed to road noise sing at higher frequencies than those living in quieter areas.

For other animals, such as microbats in England, disruptive noise changes how they forage and move around their environments.




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How noise pollution is changing animal behaviour


In extreme cases, these human-associated noises can drive animals away from their homes, as the disruptions to their lives becomes untenable.

Urban black-tufted marmosets in Brazil have been shown to avoid areas with abundant food where noise may interfere with their vocal communication. And research shows intruding noise in stopovers for migratory birds in the United States reduces their diversity by 25%, with some species avoiding the stopovers altogether.

Black-tufted marmosets in Brazil avoid noisy habitats even when there’s plenty of food.
Shutterstock

A new quiet?

The soundscape of cities in lockdown can be dramatically different from what we have come to accept as normal.

First, there are new noises. For example, in Sydney’s areas of concern subject to tighter lockdown restrictions, people are living with the frequent intrusive noise of police helicopters patrolling their neighbourhoods, making announcements over loudspeakers about compliance.

But in other cases, as our movements and activities are restricted, some city sounds associated with a negative impact on well-being are significantly reduced. People who live near major roads, aircraft flight paths, or construction sites will certainly be noticing the quiet as road traffic is greatly reduced and non-essential construction is paused.

But of course, while this silence might be golden for some, for others the sound of silence is the sound of lost work and income. This quietude may even be considered as unwelcome or even eerie — the sonic signature of isolation, confinement and loss.

The bow-winged grasshopper adapts to noisy soundscapes by singing at higher frequencies.
Quartl/Wikimedia, CC BY-SA

Just as many animals adapt to or avoid noisy urban environments, there is a chance many will respond to this natural experiment playing out. Quieter urban environments may see the return of some of our more noise sensitive species, but this depends on the species.

The Brazilian marmosets mentioned earlier didn’t return to those locations even during quieter times, suggesting the noise left a disruptive legacy on their habitat choice, well after it was experienced. On the other hand, other experiments show some species of birds rapidly returned to sites after noise was removed from the landscape.




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While it’s too early to confirm any early speculation about nature returning to quieter urban environments during lockdown, there is compelling evidence many people will benefit from engaging with local nature more actively than they did before.

Birdwatching increased tenfold in lockdown last year.
Matthew Willimott/Unsplash

Many more Australians are acting as urban field naturalists. Birdwatching, for example, increased tenfold in lockdown last year.

It’s clear people are seeing novelty and wonder in animals and plants that have survived and even thrived in our cities right beneath our noses the whole time. Our increased use of local greenspace during the pandemic has created new opportunities to find the extraordinary in the ordinary.

Rethinking post-pandemic soundscapes

What might we learn from this natural experiment about the soundscapes we take for granted and the soundscapes we actually want?

This is an invitation to think about whether we ought to do more to control sounds we consider “noise”. Yes, decibel levels of activities like car and air traffic matter. But it’s also an opportunity to think beyond controlling sounds, and consider how we might create soundscapes to enhance human and non-human well-being. This is easier said than done, given there’s no universal measure of what sounds give pleasure and what sounds are perceived as noise.

This aligns with the growing body of evidence on the need to reduce noise pollution and protect biodiversity when planning and managing our cities.

Like just about every other dimension of urban life, envisioning and creating an improved urban soundscape requires careful attention to spatial inequality and diversity – including of species – and a capacity to work through our differences in a fair and just way.




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The Conversation


Kurt Iveson, Associate Professor of Urban Geography and Research Lead, Sydney Policy Lab, University of Sydney and Dieter Hochuli, Professor, School of Life and Environmental Sciences, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

World-first continental acoustic observatory will listen to the sounds of Australia



File 20171129 28913 n3zyhs.jpeg?ixlib=rb 1.1
Solar-powered arrays can be left in remote locations, recording high-quality audio for years.
Supplied

David M Watson, Charles Sturt University

To me, the sound of a healthy wetland is like a symphony: crickets, frogs and splashing waterbirds; the dawn chorus with occasional jets flying overhead; even the odd donkey.

But add cane toads to the mix and it becomes a monotone dirge – the trilling, birdlike call of the toads and nothing else.

Healthy wetlands are a symphony of animals and sounds.
Australian Acoustic Observatory/David Watson, Author provided799 KB (download)

Once cane toads colonise an area, their cries drown out everything else.
Acoustic Observatory/David Watson, Author provided2.99 MB (download)

The significance of sound in ecosystems is what prompted my colleagues and me to develop a world-first acoustic observatory, made up of 400 permanent sensors embedded across the entire continent.

Three test sites, in inland woodlands, wetlands in Northern Australia, and subtropical forest remnants, have illustrated how we can use sound to track the movement of invasive species, the impact of climate change, and the health of remote ecosytems.

Now, with the support of five universities and a grant from the Australian Research Council, we are working to install acoustic sensors in ecosystems across Australia. By mid-2018 the full array will be in place. And once we begin recording, every minute will be made available to everybody online.

How it works

While audio has been used around the world in ecological research, Australia is the perfect candidate for a continent-wide recording array. We have many excellent ecologists and computer scientists concentrated in a small number of places, within a vast and sparsely populated country.

The difficulty of regularly visiting many parts of the nation, combined with the growth in digital technology and storage, means it is now feasible to leave recording devices in place for weeks – or in our case, years.

By the middle of 2018, 400 sensors will be installed across Australia.
David Watson, Author provided

Each array is built around a steel pole concreted into the ground. At the top is a solar panel, about the size of an A2 sheet of paper, which is connected to a battery to keep the digital recorder powered through overcast days.

We don’t yet have the ability to upload the data remotely (largely because of Australia’s lack of internet bandwidth), so for now we need to visit each array every six months or so to swap out the SD cards.

Once the data are collected, it will all be uploaded to the internet and made available for free. One of our hopes is that anyone with an interest in nature, from school teachers to artists and more people besides, will engage with this project.

Visualising time

One of the strengths of this project is our ability to use sound to picture time. We can prepare fascinating visualisations that contain months’ worth of data in a single image.

Some of the effects we’re measuring, such as the impact of cane toads and other invasive species, have very obvious acoustic signatures. They are dramatic to hear, but even more striking to see in a sonograph (essentially a graph of sound).

A 24 hour recording rendered as a false-colour spectrogram. Different sound signatures are assigned colours, making patterns over time visible.
Michael Towsey, Anthony Truskinger, and Paul Roe

We’ve pioneered the use of false-colour spectrograms to visualise long duration recordings. These make clear the flattening effect of invasive species, or the long-term subtle shifts caused by climate change.

The other major advantage of our remote arrays is that animals aren’t disturbed by humans frequently coming and going, which allows us to collect interesting and sometimes surprising data.


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Emus, for example, are attracted to shiny things – so a big shiny thing in the desert will catch their attention. And if you’ve heard them, you know they also have a pretty strange call, like a deep rolling boom.

When a big mob of 30 or so birds come across an array you can definitely hear it. From a nice quiet desert dune, with gusts of wind and small birds chirping, you’ll hear a little “oo-oo-oo”. And then there’s another, and another – and then it’s like a football crowd, with all of them investigating the array, pushing it around and mucking about with each other.

The ConversationThese continuous recordings of distinctly Australian soundscapes are surprisingly evocative. Ultimately, this acoustic observatory will not just allow environmental scientists to take the pulse of Australia’s ecosystem – it will also represent the most avant-garde radio imaginable, with 400 stations playing their own unique mix.

David M Watson, Professor in Ecology, Charles Sturt University

This article was originally published on The Conversation. Read the original article.

Koalas: Trees the Key to Growing Populations


A recent report on Koala populations has concluded that more trees are the key to growing populations and spreading habitats. Hardly sounds surprising does it – the article is linked to below.

For more visit:
http://sydney.edu.au/news/84.html?newsstoryid=6826