Soundscape Ecology: Opening your ears to conservation

The following article was published in Scottish Wildlife Magazine June 2019, issue 98, pp32-33 and is reposted with permission of Scottish Wildlife Trust.

When was the last time you stopped what you were doing and just listened? The sounds we hear can tell us much about our environment. On a spring day we might hear hungry chicks calling to be fed, children playing in the local park, a telephone ringing in a nearby house. All these sounds form a ‘soundscape’ unique to the location that you are in.

The term soundscape was coined by analogy with landscape to capture the idea that the sounds we perceive form a rich and nuanced acoustic environment. We can broadly categorise sound according to their origins. Sound created by birds, mammals, insects and other animals is termed ‘biophony’, while the sounds created by human activity is termed ‘anthropophony’. Soundscape ecology studies the relationships between these types of sound and how different organisms interact acoustically with their environment.

Many animals use sound to communicate within social groups: to attract a mate, to announce the arrival of a predator, for navigation and for territory holding. There is a rich tradition of scientists making field recordings of animal sounds across the globe, resulting in extensive audio libraries of environmental recordings covering many species – many now available online. With sound recording equipment improving all the time, it’s now possible to collect acoustic data around the clock, yielding rich information such as the presence and daily activity of certain species in a specific area. The technology has to date been used to monitor bats, birds, frogs, crickets, marine mammals, elephants and even some fish.

As well as studying specific species, researchers have tried to account for the way in which soundscapes are structured. For example, the ‘acoustic niche hypothesis’ proposes that animals such as birds and insects will tend to make their vocalisations stand out by pitching them at a frequency different to that used by other species that typically live alongside them. That is, the available frequency ranges somehow become shared out between species so that there is minimal overlapping.

It’s not surprising that there is evidence to suggest that the increasing noise that humans create, for example from road traffic and industrial activity, can have a negative effect on biodiversity. In the case of birds, anthropophony can block out sounds which signal danger and can also interfere with the messages that males use to defend their territory and to attract mates. Some species have learnt to compensate for this, with urban bird populations having different behaviours from their forest counterparts. One strategy exploits the so-called ‘Lombard effect’ – like humans at a cocktail party, birds will raise the volume of their sounds to overcome the background noise level. Other responses are to shift the time of singing activity to avoid urban rush hour, or to raise the pitch of songs to avoid them being drowned out by low-frequency traffic rumbles.

Reducing ambient noise is good for both humans and wildlife, yet mitigating the acoustic effects of road traffic – for example, by erecting noise barriers or making road surfaces more porous – is expensive and often not feasible in city centres. As well as reducing noise pollution in general, planners are recognising the importance of preserving and enhancing existing ‘quiet areas’, including parks and private gardens. From a wildlife conservation perspective, more research is required on the noise sensitivity of different animals and whether, for example, targeting noise reduction measures during the breeding season can achieve significant benefits.

In the CitySounds project, we set ourselves the goal of capturing a comprehensive ‘picture’ of an urban soundscape, using recording equipment located in trees. Initially, our focus was on the sounds that can be detected in the Meadows, a much-used city-centre greenspace in Edinburgh. Our follow-on project, ParkLife, has expanded the scope to embrace three other parks within the city and to also integrate information from social media about human use of the greenspaces. As well as looking for acoustic indicators of biodiversity, we are interested in the variety of sounds produced by human activities beyond background traffic: for example street music, festivals, recreational games, emergency sirens, and so on.

We are still in the process of collecting this unique and substantial soundscape dataset and although we have not carried out significant analysis of the data, we can begin to observe patterns. The image above spans six hours from midnight to 6am on 13 June 2018. Towards the right-hand side of the image, an increase in spectral activity is noticeable. This correlates to what we would expect around 4am on the morning in question — dawn was 3:56am in Edinburgh that day.

Longer term, we hope to be able to use artificial intelligence to detect and recognise different categories of events within a noisy city soundscape. This will give us more precise tools for understanding soundscape ecology, which in turn will help us be smarter and more effective in reducing our acoustic impact on the natural world.

CitySounds Talk at Smart Data and Smart Cities Conference

We presented an overview of the CitySounds project at the 3rd International Conference on Smart Data and Smart Cities in Delft on 4th October 2018. As you can see from the photo above, Delft was basking in warm autumn sunshine, so it was a great time for a visit.

Here’s the reference for the paper:

Klein, E., Chapple, S., Fainberg, J., Magill, C., Parker, M., Raab, C., & Silvertown, J. (2018). “Capturing the Sounds of an Urban Greenspace”. In International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. XLII-4-W11, pp. 19–26. Copernicus GmbH.

Chris Watson: Inside the Circle of Fire

On 5th April, field recordist and sound artist Chris Watson helped set the CitySounds project into a wider context by presenting recordings from his sound installation Inside the circle of fire: A Sheffield Sound Map. Before a large audience in the Reid Concert Hall, Chris guided us through a project that describes the sound world of the city of his birth in dynamic multichannel sound.

Audience at Reid Concert Hall, University of Edinburgh

As Chris said: “We tend to hear everything, but we rarely listen. We live in such a noise-polluted environment.” The event was a great opportunity to focus attention on the richness of urban sounds rather than ignoring them.

CitySounds Makes a Noise

We are lining up a number of exciting events to round off the current phase of CitySounds. Check out the details below.

Thursday 5th April, Talk by Chris Watson

3:00 pm – 4:30 pm, Thursday 5th April, Reid Concert Hall, Bristo Square

We are holding a presentation featuring guest speaker Chris Watson. Chris is a field recordist and sound artist, and will reveal sounds from his sound installation Inside the Circle of Fire: A Sheffield Sound Map, a project that describes the sound world of the city of his birth in dynamic multichannel sound.

Registration (waitlist only) and more information here:

Thursday 5th April, sonikebana v1

5:00 pm – 7:00 pm, Thursday 5th April and 2:00 pm – 5:00 pm Friday 6th April, St Cecilia’s Hall, 50 Niddry Street
Sound artist and composer Martin Parker has been listening to material recorded by Edinburgh’s CitySounds project and has been recording audio from the Meadows himself. He has placed some of these sounds inside custom-built portable loudspeakers. At this installation, visitors are invited to move the loudspeakers around the space in order to design and reorganise the soundscape as they hear-fit. The sounds playing are not fixed but actually morph-based on the direction that the speakers face — every change in position of the speaker will change the sounds you hear. Think of it as a kind of audible flower arranging.

Registration and more information here:

Friday 5th April, sonikebana v2

2:00 pm – 5:00 pm Friday 6th April, St Cecilia’s Hall, 50 Niddry Street
Sonikebana installation open to the public.

Friday 6th April, Zoë Irvine Workshop, Sensing Information from Sound

4:00 pm – 7:00 pm Friday 6th April, starting at St Cecilia’s Hall, 50 Niddry Street

Zoë Irvine is an artist working with sound, exploring voice, field recording and the relationship between sound and image. Join Zoë for a listening and recording sound walk around Edinburgh’s heartland. Rather than listening out for the usual ghouls, you’ll be listening for the noises made by people, their machines and the environmental sounds of nature too. You’ll then explore ways of revealing information about the soundscape and what everyone and everything is doing within it.

Registration (waitlist only) and more information here:

Collaborative box building

Come and help us build some wooden tree boxes, which will be installed around the Meadows with microphones inside them for the CitySounds project. This will be a great chance to learn some basic woodwork skills, whilst also contributing to an exciting community project. No previous woodwork experience required!

Please register using this Eventbrite link.

Into the Trees

Monday 12th March was something of a landmark for us: Simon finally got to install one of our Audio Capture Devices (ACDs) on a tree in the Meadows! He is using a clever combination of bungee cords and bike cables to make sure that they are firmly attached.

BACD securely attached to a branch

A few teething issues in getting the ACDs to talk the server are being ironed out, and we should be able to report back soon on what data is being collected.

In preparation for this public launch, Silje toured notice boards around the Meadows to put up information leaflets. And for those who want to know more, we’ve added a QR code to the poster that points to our Privacy Notice.

One of the Meadows Notice Boards

Site survey of trees on the Meadows

Simon Chapple and I met with Peter Davidson, one of the City of Edinburgh Council’s Park Rangers, to look at the options for installing our Audio Capture Devices (ACDs) in trees across the Meadows. Although there was a fresh wind, we were fortunate that it was a clear, sunny day to carry out our survey.

Simon and Peter sizing up a tree

To start off, Simon gave a brief introduction to his ‘bird box’ enclosures and electronic kit, and explained how they would be attached to the trees using bungee cords, plus a padlocked cable for security.

Screen grab showing 2 bars for the organicity WiFi Access Point
We then did a quick tour of parts of the Meadows where we could see that we were in range of the newly-installed WiFi Access Point, appropriately enough named ‘organicity’, The main challenge was to find trees with branches in the ‘goldilocks’ zone: high enough for the ACDs to be out of harm’s way, but not too high for us to change the battery if necessary. (No, we haven’t yet got the point where we can use solar panels or tap into the power source of lamp posts!) Another constraint is that we need to avoid trees which have been marked as possibly suffering from Dutch Elm Disease, though fortunately that doesn’t seem to be too prevalent on the Meadows.

Two views of the Community Garden supported by Greening our Street and FOMBL

We concluded with the happy feeling that there was a good number of trees that we could use when we are ready to launch the devices in public.

Project Kick-off Meeting

Although we held a number of meetings between different partners during the inception phase of the experiment, it was only on 4th December 2017 that most of us managed to meet face-to-face in the Alt-W LAB in Edinburgh’s City Art Centre.

After a quick review of the project deliverables, milestones and schedule, Simon Chapple provided an update on the audio capture framework and plans.

Graham Stone pointed out that it will be important to be able to correctly interpret *missing* audio data, such as the absence of certain bird sounds. He suggested that one way of providing a baseline of detectability would be to play pre-recorded samples of wildlife sounds at natural levels to determine the sensitivity range of sensors.

We agreed on the importance of providing transparent information about the project to relevant stakeholders and the general public. This will be addressed in the New Year as we make more progress on understanding the technical dimensions of the project.

Finally, we discussed the fact that we have very Little time to prepare the end-of-project sound installation, and planning the content and requirements for this will have to be addressed as soon as possible.