Science and Culture: Artists and scientists come together to explore the meaning of natural sound
Amy McDermott
David Monacchi has spent the last 20 years hiking into some of the most remote habitats on Earth. He’s canoed through flooded Amazonian forests and tread deep into the jungles of Southeast Asia and Africa. But he isn’t on a quest for rare animals or for samples of their remains. Monacchi, a composer, is hunting for the ecosystem’s sound.
Sound is everywhere in tropical forests. Rain drips from water-slicked leaves, birds screech, monkeys titter and bellow, branches crack, wind moans, and insects chirp and buzz. Vibrations pierce the humid understory and echo through the airy canopy, creating a symphony of sounds that speaks to both artist and scientist.
Monacchi is harvesting artistic inspiration as well as data. The chirps and rattles contain information about how species interact with the environment and each other, as well as the health of the habitat. Sometimes Monacchi uses his recordings to inspire the public, sometimes to inform ecological research. “I’m trying to be at the edge of both worlds,” he says.
People straddling music and science often have a variety of titles. Monacchi usually describes himself as an interdisciplinary artist. Sometimes he prefers sound engineer or ecoacoustic composer.
Likewise, names for this field vary. For ecologists, the study of sound’s role in ecological processes is ecoacoustics (1). For composers, it’s soundscape ecology or acoustic ecology. Labels fall away as creative specialists in the arts, the natural sciences, or both come together to collaborate. They work with environmental sound for a variety of reasons — sometimes musical, sometimes scientific, and sometimes both. All strive to understand and explore the environment using sound.
Sound Science
Monacchi first hatched the idea for his project, Fragments of Extinction, in 1998, a few years after biologist E. O. Wilson estimated some 30,000 species disappear every year (2), numbers rivaling the five mass extinctions of the geologic past. Horrified by the scope of loss, Monacchi set out to collect sound portraits of primary equatorial forests and capture the aural complexity of these last undisturbed environments. His ultimate goal is to play them for the public in art and science museums, inspiring reflection on all the species that could disappear. The recordings are also a reference for future generations, he says, to be able to look back on these ecosystems, if and when they are damaged.
It’s not easy to capture the sonic complexity of a forest. Sound comes from near and far, from above and below. Record a forest on the dual audio channels of a smartphone, for example, and the playback from its single speaker will seem to emanate from a single point. To reconstruct realistic wild habitats, with sounds coming from all directions, Monacchi records 24-hour sound portraits of virgin forests, using state-of-the-art technology with numerous microphones and channels (Audio S1 and S2*).
He plays his recordings for the public in specially built theaters in Denmark and Italy, which are studded with up to 43 custom-built high-definition speakers on the walls, floor, and ceiling to recreate the sphere of sound around a listener. “We are taking samples of this fantastic heritage,” Monacchi says, “and we are bringing them back to the people of museums, in order to reflect on the beauty, the fragility, the complexity, the balance of these habitats.”
To study the Fragments of Extinction recordings, Monacchi partnered with naturalist Almo Farina, an ecoacoustics pioneer based at The University of Urbino in Italy. One central tenet of the field, Farina explains, is that animals hear and recognize certain sounds, interpret them, and change their behavior accordingly. An environment’s acoustic complexity, quantified as the number of sound events in a recording, offers a glimpse of the many signals that organisms use to navigate their surroundings, select suitable habitats, and track resources.
Identifying acoustic events in a sound file can help ecologists parse the interplay of animal vocalizations with other natural and man-made sounds, such as a burbling creek or a gunshot (3). It may also offer insight into the health of the environment, at scales from individual species to communities (4). For example, two years after a devastating 2011 wildfire ripped through southeastern Arizona’s sky islands — isolated mountains rising from the intersection of the Sonoran and Chihuahuan Deserts — insect communities remained relatively quiet. Their sounds were only audible in recordings from 18% of burned sites, compared to 55% from non-burned locations, offering land managers valuable insight into the ecosystem’s recovery after the burn (5).
A major challenge for the young field of ecoacoustics is standardizing methods to identify and count acoustic events. Farina published an approach in 2016 that scans audio files for sound’s complexity and evenness. He now wanted to apply his method, called EEDI, to two of Monacchi’s 24-hour recordings from raucous, undisturbed forests in Borneo and Ecuador, likely two of the most acoustically rich habitats on the planet, Farina says. He expected their sound complexity to behave something like a fractal, with greater intricacy at finer scales.
“You can hear the dynamics of the glacier unfolding.”
— Matthew Burtner
To test this prediction, Farina used EEDI to break each sound file into six-minute chunks, which he analyzed for audio events. Then he repeated the process at 10 finer timescales, down to one second. His results matched his prediction. “The more fine-grain the scale, the more codes you find,” Farina says. “It’s not the presence of individual codes that’s important, but the behavior of codes across a sequence of scales.” Validating the EEDI methodology is a step toward standardized analyses in ecoacoustics, Farina says, which can help ecologists judge habitat quality and landscape change.
Cases such as this illustrate the power of sound as scientific data, but it does have limitations Farina says. For one, not all species vocalize or rely on their hearing. Some lean on other senses, such as sight, touch, and smell, to interpret their environment. Methods to collect acoustic data are also far from standardized, he says, and metrics to extract information from audio files are also limited.
Even so, sound naturally fosters interdisciplinary efforts such as Farina’s and Monacchi’s by drawing artists to scientists who know the latest analytical techniques, says soundscape ecologist Bernie Krause. The medium, Farina adds, also draws scientists to artists, who often have better audio equipment and better-honed communication skills. “Our aim is the same,” he says, “to collect information to inform people.”
Sound Inspiration
Artists often strive to recreate soundscapes: to bring the experience of a rainforest or thundering ocean into a concert hall, radio performance, or exhibition space. Evoking an artistic sense of faraway lands sometimes involves warping and manipulating recordings and playing them in combination with the original sound files.
Composer Hildegard Westerkamp’s piece Beneath the Forest Floor carries listeners into the extreme quiet of Vancouver Island’s old-growth forests. It begins with a low thumping sound — a recording of a raven’s call, slowed down. Westerkamp captured it and many other sounds on Vancouver Island in British Columbia, Canada, then wove them together in a digital studio in Toronto. When Westerkamp first heard the raven, she wasn’t sure how it would feature in her creative process, but “when I slowed it down, it sounded like drumbeats. It became an instrument,” she says. This audio trick echoed the traditional mythology of West Coast cultures, in which the raven is a symbol of mischief.
Westerkamp also sought to share both the stillness and majesty of the forest’s towering trees. “Not only did I want to evoke the feeling of being there,” she says. “But more importantly I hoped that it would motivate listeners to go to these environments and experience them first-hand.”
Director Gus Van Sant heard something more in Westerkamp’s recordings. He used an excerpt of the song in his 2003 film Elephant — which was inspired by the tragic 1999 school shooting in Columbine, CO — to punctuate the chilling moment when the shooting begins. “He made me aware in hindsight of how dark my piece actually is, of the fearfulness and mystery of the forest,” Westerkamp says. “It highlighted for me once again, how differently we all listen.”
Sometimes evoking an environment means combining sounds in unexpected ways. Ecoacoustic sound artist Matthew Burtner makes sonic portraits of glaciers, which he calls sound casts, using field recordings to represent the whole geologic feature in a single piece (Audio S3†). Glaciers are impressive sights, but images don’t capture the slow-motion grinding, living quality of these dynamic rivers of ice, Burtner says. Through their cracks, booms, trickles, and bellows, he hears glaciers come alive.
To make his glacier sound casts, Burtner installs a variety of microphones and hydrophones over a glacier. Some sit on its snowy surface, others hang down into crevasses, and still others rest in trickling meltwater streams. He uses rough-and-tumble microphones typical of geology research to pick up sounds in mud pits and other low-gurgling, crunching places and hydrophones suited for marine mammal research to catch high frequencies.
Back in his studio, Burtner pipes his recordings through an array of speakers spread around the room. He, like Monacchi, aims to capture the three-dimensionality of sound. Burtner arranges the speakers so that a listener in a gallery or concert hall would “hear a crack of ice on your right and then hear it traverse the glacier and be on your left a millisecond later,” he says. “You can hear the dynamics of the glacier unfolding.”
What emerges is an impression that even a mountaineer couldn’t experience in person. Booms and echoes of the entire glacier, recorded from its craggy peaks down into icy cracks where no hiker could go, surround the listener simultaneously.
Sonic Collaboration
Often, artistic and scientific sound projects aren’t so different. Recording and editing sound files, whether animal calls or the pops and thumps of a glacier, require a complex knowledge of instrumentation and software, Monacchi says. “For us, dealing with science was never that far away.”
That was certainly the case for soundscape ecologist Krause. Working as a professional studio musician in the 1960s and 1970s, Krause played for pop artists George Harrison, Van Morrison, and The Doors. Then in 1970, he and Paul Beaver released the album In a Wild Sanctuary, which incorporated natural soundscapes. Thus began Krause’s journey to investigating natural sounds. He made high-quality recordings of whole habitats in his free time, intrigued by their acoustic structure.
After finishing his doctorate in creative sound arts in 1981, with a focus on bioacoustics, Krause developed his niche hypothesis: in healthy habitats, different species vocalize in unique bandwidths, each occupying their own acoustic territory (6). Krause found that these territorial boundaries tend to disappear in stressed environments. The collective sound of the habitat becomes chaotic as the organisms still present vie for acoustic territory, searching for new, available frequencies or new times to hoot and titter.
At Sugarloaf Ridge State Park in Sonoma County, near Krause’s longtime home in Northern California, he documented an encroaching quiet, coinciding with the state’s prolonged drought. Krause has been recording every spring at Sugarloaf Ridge since 1993, and he documented the sounds of birds, insects, and other life dropping progressively from 2011, with a sharp drop in vocalizations in 2015.
Krause published the findings in an article, coauthored with Farina, on sound as a way to study climate change impacts in 2016 (7). He and Farina are now working on a second collaboration, with ecologist Jerome Sueur of the National Museum of Natural History in Paris. Since California’s historic 16-year drought ended in 2017, Krause is hopeful for the Sugarloaf site. Heavy spring rains have called it back to sonic life, he says.
Ecologists and artists converge around acoustics because they know sound reveals otherwise-hidden dramas about both the natural world and humans’ relationship to it. Working together, colleagues across disciplines can “use the power of science to understand phenomena,” Monacchi says. “And use the power of art to share phenomena with the broad public.”
