Welcome to The Undark Podcast, which will deliver — once a month from September to May — a feature-length exploration of a single topic at the intersection of science and society. In this episode, join writer and musician Adam Boffa and podcast host Lydia Chain as they explore the field of acoustic ecology — where scientists are finding signs of climate change in nature’s symphonies and working to document the soundscapes that may disappear forever.
[Audio of baseline Barker Dam]
Adam Boffa: For nearly 10 years, Garth Paine has crossed the rocky landscape of Joshua Tree National Park to reach one of his favorite recording spots: Barker Dam. He’d lie on the ground in the summer heat while his recorder captured his sonic environment.
Garth Paine: I like to record for 2-3 hours at a time. And what that does is it really connects me to the kind of energy of the place.
Adam Boffa: Paine is an acoustic ecologist — he uses sound to get a richer understanding of an environment. And on one such trip, what he heard surprised him.
[Transition audio clip to wet Barker Dam]
Adam Boffa: This familiar recording site, he says, was “completely transformed.”
Garth Paine: And so what I ended up recording and listening to many times as that water stayed there for some time was, you know, an entire ecosystem that I’d never heard there before.
Lydia Chain: Welcome back to the Undark Podcast. I’m Lydia Chain. We’ve got a lot of great stories lined up for this season, and I’m excited to share them with you. Just a quick note — whenever possible, our reporters use best social distancing practices to record in-person tape. And, where that was not possible, they used phone and internet interviews to keep themselves and their sources safe. Back to the show.
Improvements in audio processing and recording equipment have allowed scientists unprecedented insight into the soundscapes of the planet. But the field has been born into a world already in the middle of a changing climate.
Some acoustic ecologists are attempting to generate the data necessary to answer deep questions about how the environment and its inhabitants are changing, and others are using sound to address specific conservation issues, or to politically engage communities. And some are rushing to capture as many soundscapes as possible before they are gone forever. Adam Boffa has the story.
Adam Boffa: Months before Paine captured that transformed ecosystem at Barker Dam, unusually heavy rains filled the dam’s reservoir, drawing in birds, frogs, and insects he’d never heard there before.
Garth Paine: You know, things have been so crazy that, that patterns have become much more chaotic. Normally, that dam is either dry or it has a tiny little puddle of water. And, you know, everybody else was like, “Oh, wow, we haven’t seen water here for decades.”
Adam Boffa: Paine co-founded the Acoustic Ecology Lab at Arizona State University in 2015 and he says there’s a lot to learn from a place’s soundscape.
Garth Paine: Sound describes the environment in really detailed ways. Every animal within that ecosystem has a sonic niche, and every environment therefore has a kind of cumulative sonic signature. And that signature is made up of all of the species that are present there.
Adam Boffa: The physical environment — things like air temperature, foliage density, building materials, or the composition of rock formations — also contributes to that sonic signature by changing the way sound travels and reverberates. And of course, nonliving things like running water or thunder also shape the sound of an environment.
Acoustic ecology as a field is just beginning to explore and quantify Earth’s soundscapes and apply that knowledge to environmental health problems. But the rich variety of sounds available to study has already started to transform. The time to record and analyze some of the planet’s most diverse and important soundscapes may be running out, and scientists are rushing to find the best ways to research and understand the planet’s changing ecosystems.
Paine likes to use the example of declining Joshua trees to explain what a change in a soundscape can reveal. Over the last few years, a malignant fungal disease, invasive grasses, wildfires, and climate-related heat stress and lack of water have all contributed to a “clear and notable” reduction of Joshua trees in the park, he says.
Garth Paine: The Joshua trees are the principal larger plant life there. And so, plant life and foliage generally absorbs a lot of sound. And so, if you think about the fact that the foliage in the Joshua trees might be reduced, then in fact the reverberation qualities in that environment will change over time.
Adam Boffa: Joshua trees absorb and redirect sound frequencies, which affects what other species hear, and thus, how they might behave. So if there are fewer trees, there might be consequences for other animals in the ecosystem.
Garth Paine: And it could be, actually, that through these processes those environments become less suitable as habitat for species that are currently there, because increased reverberation might mean, for instance, that predators can’t really quite hear exactly where the prey is, that animals can’t communicate well enough during breeding season or just for general survival, and they might have to move.
Adam Boffa: Acoustic ecology can provide an unusually fast way to grasp these kinds of changes as they happen. Amandine Gasc works at the French National Research Institute for Sustainable Development, a public agency. There, she uses acoustic ecology in conservation efforts and to monitor ecosystems that have been disturbed or disrupted in some way. For example, the spread of Wasmannia auropunctata — the electric ant, or little fire ant.
Amandine Gasc: So, it’s a small ant but very invasive in New Caledonia and in other parts of the world, as well. What happened is, like, the ant is spreading and affects a lot of the local fauna. So, the local fauna disappears — especially crickets, are very abundant. So, when the ant is here, the ant kind of silences the forest. Because we show that crickets in this environment are responsible for 85 percent of the acoustics at nighttime in the forest. And so, it’s a group that contributes a lot.
Adam Boffa: Here’s what they sound like.
[clip of crickets]
Amandine Gasc: So, when they are not there, you for sure hear it — it’s super silent.
[clip after ant]
Adam Boffa: When ants invade, the chorus of crickets dims to a few lone voices.
Other ecologists had already documented the way these ants kill off native insects in other places. What acoustic ecology offered Gasc and her peers was a quick, easy, non-disruptive way to recognize their presence in New Caledonia.
Amandine Gasc: Traditionally, to have information of the animal community you have to do inventories of species, so you need an expert in every taxonomy group, you need to go on the place, and most of the time you need to collect the species to be able to recognize them. So, it’s actually very difficult work, and requires a lot of human time on the field.
Adam Boffa: Gasc says that pairing acoustic ecology with established research lets her team quickly spot discrepancies in soundscapes so they can make a conservation plan. But applying those techniques to the largest conservation problem — climate change — has some unique challenges. If a soundscape changes as weather, temperature, and animal activities change …
Garth Paine: That of course changes across the seasons, but it also changes over time with climate impacts. So, you might get more of one species or less, or you might get species that didn’t used to be there. So, you know, you’re hearing calls that perhaps are not common and over time that might become more common.
Adam Boffa: But making definitive claims about exactly what is changing typically requires years of observation and heaps of data. That’s a challenge for an emerging field like acoustic ecology.
Amandine Gasc: Yeah, I think this field is too recent … It doesn’t have enough data to do scientific analysis and statistically show that, OK, yes, we are sure that this changed like this or this changed like that. So, I think people … some scientists or people interested in the field observed it along their life, but we don’t have the data to, like, prove it through the scientific methodology right now.
Adam Boffa: Scientific methodology requires even the most seemingly obvious claim to be thoroughly backed up by evidence. And for many acoustic ecology projects, that data just isn’t there yet.
Amandine Gasc: So, we’re pretty sure that it’s changing. There’s no way that sound doesn’t change but the species are. Like, it for sure goes with the species that are locally shifting and changing. But we don’t have data to, like, support or show any results right now. But a lot of people are trying to put long-term projects right now, to, like, have it in like 30 years maybe or 50 years, enough data to show the changes in an acoustic environment.
Adam Boffa: Building that kind of database is one of the goals in Paine’s lab. There are a few studies with that historical data, which show the sort of insight the field could provide into how ecosystems will change under the pressures of climate change. While pursuing her doctorate in ecology and evolutionary biology at Rice University, Shannon Carter joined a project where researchers had recorded the sound around eight ponds in northeast Texas every year since 2000. At the time, that gave her 15 years’ worth of frog mating calls.
Shannon Carter: There were a lot of fundamental ecological questions that we didn’t know anything about, and that was the main motivation of originally installing the recorders.
Adam Boffa: According to Carter, these frog ponds are ideal habitats for acoustic ecologists. They don’t move, and the frogs return to them year after year, so recording devices placed there can be expected to provide reliable audio. And the sounds frogs make serve a purpose.
Shannon Carter: So, frogs call when they’re breeding. Using the frog calls is a really neat proxy for this biological event. The calling of the species indicates they’re reproducing, and that their offspring are going to be in the environment a short time afterwards.
Adam Boffa: Each species’ reproduction is timed to specific environmental cues.
Shannon Carter: Historically, these frogs have called, like, one species in early May, next species late May, and kind of have this sequence where one came after the other. And this reduces competition between their offspring.
Adam Boffa: But with changes in temperature and rainfall patterns, this rhythm can become disrupted, and frog species struggle to separate their mating seasons.
Shannon Carter: One of the big things that we pulled out of this data was that they’re not doing that as well anymore, partly because the availability of resources is getting more pulsed because of the patterns of rain in east Texas. So now we’re seeing, OK, these species that used to call one after the other are all calling at the same time of year now. And that means that all of their tadpole offspring are going to be in the pond at the same time competing with one another.
Adam Boffa: That disruption has a big impact.
Shannon Carter: We’re going to see much lower survival, and probably, fewer frogs the next year — lower recruitment.
Adam Boffa: Though Carter’s research looked specifically at frogs, she says that behavioral changes in response to climate change have been observed in other species, many of which rely on each other. But there isn’t always uniformity to these changes. As these different behaviors fall out of sync, the effects multiply, which can create existential problems for the viability of an ecosystem.
Shannon Carter: Since not all species are responding the same way, we’re seeing a lot of important ecosystem interactions getting disrupted. And this can lead to a sort of cascade throughout food chains and ecosystems where we see kind of reverberating effects through natural systems.
Adam Boffa: The cascading impacts of ecological change that Carter describes can eventually mean the loss of entire soundscapes — sometimes permanently. The disappearance of natural sounds is a phenomenon David Monacchi has studied for almost two decades.
Monacchi is a professor at the Conservatorio Rossini in Pesaro, Italy and he launched the Fragments of Extinction project in 2002. He worked with Greenpeace on an initial field recording trip to the Amazon, where he hoped to document remote rainforest habitats — areas that posed challenges for travel and for his recording equipment. He says the soundscape made an immediate impression on him. He saw evolution acting as a composer of ecological symphonies.
David Monacchi: So, the project from the beginning was called Fragments of Extinction because we are really aware of doing a minimum of the richness, of the incredible variety of species, and of ensembles of species, of acoustic situations that you can find.
Adam Boffa: Over time, though, Monacchi realized that his recordings might be the only surviving documentation of these sounds before pressures like climate change and deforestation took their toll.
David Monacchi: We sampled soundscapes in central Africa in the Congo Basin, in several areas in the Amazon, in Borneo, and then back in the Amazon again. Then we are going now in Sumatra and West Papua to do some more work.
Adam Boffa: Here’s a sample of a recording made in Malaysia in 2012.
David Monacchi: We are starting to have a collection of what’s changing while we’re talking.
Adam Boffa: Monacchi notes, for example, that recordings made in the Amazon back in 2002 might be impossible to replicate today. Habitat loss and extinctions mean that some of those sounds might not exist there in the same way anymore. But he doesn’t feel the need to check that those sounds have been lost.
David Monacchi: There is not any more time to confirm. We know that the extinction crisis is profound and severe and will be more severe as soon as climate changes will progress. Even if we had those data, we are only confirming what everybody’s saying — that the extinction crisis is going on.
Adam Boffa: His focus, then, is not on collecting data to track changes in an individual environment, but instead on capturing what’s there now, before it’s gone. He calls it a kind of sonic archaeology.
David Monacchi: We are not doing a quantitative analysis to trace environmental changes, species changes, ecological, and ecoacoustics changes in the environment we record. We are making heritage. We are trying to do, as soon as possible, in as many places as possible, with priority into places which are completely primary, completely undisturbed, and historically never touched — completely free of human noises and disturbances.
Adam Boffa: Paine and ASU’s Acoustic Ecology Lab co-founder Sabine Feisst hope to encourage awareness of these issues by engaging the local community. Here’s Feisst.
Sabine Feisst: And so it’s not a specialist task, acoustic ecology. Everybody can practice and everybody can experience climate change, and everybody can hear actually how things are changing.
Adam Boffa: Another benefit of bringing acoustic ecology into the community is the creation of field recordings at a bigger scale, thanks to the help of local volunteers. These efforts amount to “terabytes and terabytes” of audio data from the surrounding areas, according to Paine. It’s a database he hopes can eventually contribute to studies of climate change.
Recent advances in portable recording devices have made this a more accessible prospect. It’s easier to get more audio, and at a much higher quality, than ever before. But there’s still a gap between what your average smartphone can capture and what’s needed for research. At the Acoustic Ecology Lab, they employ more specialized equipment.
Garth Paine: But also, we use a recording process called ambisonic recording. Ambisonic recording uses four microphone capsules to record a full sphere of sound. And a key reason for that is that, if we’re looking for changes in the recording over time, if we were recording just the stereo pair pointing in the same direction every time, all of the key changes might occur behind us.
Adam Boffa: It’s not just the recording itself — how it’s captured, and how the data is analyzed still requires specialized knowledge. Here’s Gasc.
Amandine Gasc: Also, I think, passing the methodology to other people, like, the knowledge is not that easy. It’s easy to understand, like, the global idea of it, but how to use it, it’s not that easy. Like, the protocol, the standardization of the measurements, all of that is very necessary for people to work together. Also, to have, like, the same tools to work and share, like, the results and compare results.
Adam Boffa: There’s also the issue of how to turn all of this raw audio into something more manageable and comprehensible. Regular recording projects might eventually accumulate hundreds or thousands of hours of audio.
Shannon Carter: We had somebody listen to all of this recording and process and identify the species, by, manually. So, we have 48 minutes of audio each day, times 365 days, times 20 years … it sums up to days and days and days of audio recordings that my collaborator processed all on his own, and listened to each minute, and identified which species was calling. He did it piecewise, as it was coming through. I mean, several times a year, listen to everything up to that point.
Adam Boffa: Software can help automate the analysis of that data, but not entirely. It’s a big bottleneck in the process.
Shannon Carter: And there are some things to kind of shorten it, like he can use software to skip through the quiet parts. But you know, I say it’s passive data collection — you’re still having to spend massive, massive amounts of time on the other end to process it.
Adam Boffa: Once that data is collected, acoustic ecologists often try to find ways to share it with a wider audience. Some use their recordings for creative work or share them for public listening and use. Feisst came to acoustic ecology from a musicology background and believes she has a responsibility to use her work for political and community engagement.
Sabine Feisst: You wonder, you know, can I just continue doing what I have been doing when the world is on fire, you know? Do we have something to bring to the table? Maybe we have more power as musicians and music scholars than scientists who can, of course, collect data and then present the data in charts and so forth. But people are not touched by it, or they are overwhelmed and, in their helplessness, just kind of close their eyes and ears.
Adam Boffa: Monacchi has used his recordings to create surround sound installations that people can visit. Inside, Monacchi tries to create spaces that approximate the feeling of being in — and listening to — a rainforest.
David Monacchi: I had the need to bring back to people these soundscapes … because putting yourself in headphone and pretending to be in a forest is something very different than to build an environment around the audience where the forest can really acoustically live, breathe.
Adam Boffa: To do this, Monacchi and his collaborators start by creating field recordings with 38 specialized microphones that also record data regarding the location and distance of sounds. These 38 tracks are then played back through a variety of large speakers in a spherical venue called the Eco-acoustic Theatre.
Like Feisst and Paine, Monacchi believes that experiencing these sounds might help people reconnect with, and more deeply appreciate, the natural world. Which, they hope, could later inspire political action.
David Monacchi: The fact that life on Earth is quickly, quickly, very quickly disappearing is not going into the first pages of the newspapers, as it should be. So, if there is a social role and political role, it’s this one. It’s to bring straight portraits to the people and to say, should we do whatever we can as fast as possible, to save as much as possible?
Adam Boffa: But outside of that, Monacchi sees another, more immediate utility to his work. The unavoidable reality, he says, is that time is running out for people to hear certain soundscapes firsthand. Within decades, a significant portion of the biodiversity of this planet could disappear. And its sounds will follow.
David Monacchi: The aim of Fragments of Extinction is to have something in our hands to give to our nephews and say, hey, guys, this is what nature produced in the acoustic world of its complex ecosystem behavior over the last millions of years — to give to our future generations the possibility to immerse themselves into something that was as near as possible to the original configuration of the acoustic signals of an acoustic ecosystem of a primary forest before the expected severe changes of climate change, which are right now happening.
Lydia Chain: Adam, thanks for bringing us this story and joining us on the show.
Adam Boffa: Thank you, thank you for having me, thank you for the opportunity.
Lydia Chain: Audio ecology is one way of looking at an ecological space. How does it dovetail with more traditional methods?
Adam Boffa: I think, you know, particularly for a field that is relatively new like acoustic ecology and as some of the people that we interviewed mention, there just isn’t quite the volume of data yet to make some of the same conclusions that other fields have already established. But as a result, they can often sort of work together, they can sort of lean on each other a little bit. And so you have, for example, Dr. Paine talking about Joshua trees and a lot of that research isn’t exclusively found through sound studies. It’s through a combination of observation in other fields.
Lydia Chain: You mean studies that look at weather data, or behavioral observations of the creatures that live there, or analyses of species makeup … those kinds of things?
Adam Boffa: Sure, yeah, I mean, I think they try to find ways to add nuances or things that maybe aren’t able to be found in those fields either so there’s sort of a little bit of a kind of necessary interdependence there in order to make some of the more perhaps bolder novel claims the field is trying to produce.
Lydia Chain: You’ve mentioned that this is a relatively new field. How did it come about, where are its roots?
Adam Boffa: Yeah, so my understanding is that it really starts in the late ‘60s. And in particular this name, like the title of acoustic ecology, is rooted in … There’s a university in Canada where researchers were starting to develop these ideas around the sort of interplay in the dynamics between human-generated sound and then sound that came from the natural world. And they were concerned about, are there impacts of human-generated sound, you know things like noise pollution. Are there impacts of those sounds on other species, and also are there impacts on people, on human communities. And as they started to figure these things out, many of these people had backgrounds in not just the sciences but also the creative fields or the humanities. They were interested not just in scientific solutions but social solutions as well — policy solutions, community-based initiatives, that sort of thing. And so there’s very much a focus over the years on maintaining acoustic ecology as a kind of umbrella term, as a very big tent so that it encourages people coming in from artistic fields, creative fields, policy, all that sort of stuff.
Lydia Chain: That’s something I noticed in the piece as well. You have some sources very interested in answering specific scientific questions and others, like Feisst, with hopes of using sound for political engagement. Can you elaborate on that intersection between the disciplines?
Adam Boffa: I think because of those roots, because of its foundations, it has always been a field that has been interested in extending its reach beyond the sort of typical academic institutions or whatever you might call it. It’s very much been about trying to find ways to engage people where they are, sort of locally, engaging them with the soundscapes that are around them. And then also it’s trying to facilitate collaboration within disciplines. Sometimes that means trying to work on policy proposals, sometimes it means working on artistic projects, or collaborative sound installations, that kind of thing. And so if you were to go and look and see what acoustic ecologists are up to online or whatever, that sort of thing, you would often find a lot of creative works or you would find people who are doing things that are not necessarily about quantitative audio data analysis. Again very intentionally, it’s very intentionally designed to be a broad field and I think they are often interested in trying to find the ways that the science and the humanities sort of overlap or intersect or potentially benefit each other. That’s their hope, I think.
Lydia Chain: Adam Boffa is a writer and musician from New Jersey. Thanks to all of our sources that provided tape to illustrate this piece. Our theme music is produced by the Undark team and additional music comes from Kevin MacLeod at Incompetech. I’m your host, Lydia Chain. See you next month.