CEC N CULTURE AND SCIENCE

SCIENCE AND CULTURE

Artists and scientists come together to explore the meaning of natural sound Amy McDermott, Science Writer

David Monacchi has spent the last 20 years hiking into how species interact with the environment and each some of the most remote habitats on Earth. He’s ca- other, as well as the health of the habitat. Sometimes noed through flooded Amazonian forests and tread Monacchi uses his recordings to inspire the public, deep into the jungles of Southeast Asia and Africa. sometimes to inform ecological research. “I’m trying But he isn’t on a quest for rare animals or for samples to be at the edge of both worlds,” he says. of their remains. Monacchi, a composer, is hunting for People straddling music and science often have a the ecosystem’s sound. variety of titles. Monacchi usually describes himself as Sound is everywhere in tropical forests. Rain drips an interdisciplinary artist. Sometimes he prefers sound from water-slicked leaves, birds screech, monkeys engineer or ecoacoustic composer. titter and bellow, branches crack, wind moans, and Likewise, names for this field vary. For ecologists, insects chirp and buzz. Vibrations pierce the humid the study of sound’s role in ecological processes is ecoa- understory and echo through the airy canopy, creat- coustics (1). For composers, it’s soundscape ecology or ing a symphony of sounds that speaks to both artist acoustic ecology. Labels fall away as creative specialists and scientist. in the arts, the natural sciences, or both come together Monacchi is harvesting artistic inspiration as well as to collaborate. They work with environmental sound for data. The chirps and rattles contain information about a variety of reasons—sometimes musical, sometimes

In February 2016, David Monacchi sets up the three-dimensional recording systems for the circadian 24-hour continuous recording in terra firme primary forest habitat in the Tiputini River area, Yasunì National Park near Coca, Ecuador. Image credit: Alex d’Emilia (photographer).

Published under the PNAS license. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1908588116/-/DCSupplemental.

12580–12583 | PNAS | June 25, 2019 | vol. 116 | no. 26 www.pnas.org/cgi/doi/10.1073/pnas.1908588116 Downloaded by guest on September 30, 2021 Musician Matthew Burtner makes field recordings of Alaska’s Matanuska Glacier in June 2014 as part of a sound cast (Audio S3). Image credit: Matthew Burtner.

scientific, and sometimes both. All strive to understand with up to 43 custom-built high-definition speakers on and explore the environment using sound. the walls, floor, and ceiling to recreate the sphere of sound around a listener. “We are taking samples of Sound Science this fantastic heritage,” Monacchi says, “and we are Monacchi first hatched the idea for his project, Frag- bringing them back to the people of museums, in ments of Extinction, in 1998, a few years after biologist order to reflect on the beauty, the fragility, the com- E. O. Wilson estimated some 30,000 species disap- plexity, the balance of these habitats.” pear every year (2), numbers rivaling the five mass To study the Fragments of Extinction recordings, extinctions of the geologic past. Horrified by the Monacchi partnered with naturalist Almo Farina, an scope of loss, Monacchi set out to collect sound por- ecoacoustics pioneer based at The University of traits of primary equatorial forests and capture the Urbino in Italy. One central tenet of the field, Farina aural complexity of these last undisturbed environ- explains, is that animals hear and recognize certain ments. His ultimate goal is to play them for the public sounds, interpret them, and change their behavior in art and science museums, inspiring reflection on all accordingly. An environment’s acoustic complexity, the species that could disappear. The recordings are quantified as the number of sound events in a re- also a reference for future generations, he says, to be cording, offers a glimpse of the many signals that or- able to look back on these ecosystems, if and when ganisms use to navigate their surroundings, select they are damaged. suitable habitats, and track resources. It’s not easy to capture the sonic complexity of a Identifying acoustic events in a sound file can help forest. Sound comes from near and far, from above ecologists parse the interplay of animal vocalizations and below. Record a forest on the dual audio channels with other natural and man-made sounds, such as a of a smartphone, for example, and the playback from its burbling creek or a gunshot (3). It may also offer insight single speaker will seem to emanate from a single into the health of the environment, at scales from indi- point. To reconstruct realistic wild habitats, with sounds coming from all directions, Monacchi records 24-hour vidual species to communities (4). For example, two sound portraits of virgin forests, using state-of-the-art years after a devastating 2011 wildfire ripped through ’ — technology with numerous microphones and channels southeastern Arizona s sky islands isolated mountains (Audio S1 and S2*). rising from the intersection of the Sonoran and Chihuahuan — He plays his recordings for the public in specially Deserts insect communities remained relatively quiet. built theaters in Denmark and Italy, which are studded 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 *Audio credit: David Monacchi. the ecosystem’s recovery after the burn (5).

McDermott PNAS | June 25, 2019 | vol. 116 | no. 26 | 12581 Downloaded by guest on September 30, 2021 A major challenge for the young field of ecoacous- other sounds on Vancouver Island in British Columbia, tics is standardizing methods to identify and count Canada, then wove them together in a digital studio in acoustic events. Farina published an approach in 2016 Toronto. When Westerkamp first heard the raven, she that scans audio files for sound’scomplexityand wasn’t sure how it would feature in her creative process, evenness. He now wanted to apply his method, called but “when I slowed it down, it sounded like drumbeats. EEDI, to two of Monacchi’s 24-hour recordings from It became an instrument,” she says. This audio trick raucous, undisturbed forests in Borneo and Ecuador, echoed the traditional mythology of West Coast cul- likely two of the most acoustically rich habitats on the tures, in which the raven is a symbol of mischief. planet, Farina says. He expected their sound com- Westerkamp also sought to share both the stillness plexity to behave something like a fractal, with greater and majesty of the forest’s towering trees. “Not only intricacy at finer scales. 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 “You can hear the dynamics of the glacier experience them first-hand.” unfolding.” Director Gus Van Sant heard something more in ’ —Matthew Burtner 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 test this prediction, Farina used EEDI to break to punctuate the chilling moment when the shooting “ each sound file into six-minute chunks, which he an- begins. He made me aware in hindsight of how dark alyzed for audio events. Then he repeated the process my piece actually is, of the fearfulness and mystery of at 10 finer timescales, down to one second. His results the forest,” Westerkamp says. “It highlighted for me matched his prediction. “The more fine-grain the once again, how differently we all listen.” scale, the more codes you find,” Farina says. “It’s not Sometimes evoking an environment means com- the presence of individual codes that’s important, but bining sounds in unexpected ways. Ecoacoustic sound the behavior of codes across a sequence of scales.” artist Matthew Burtner makes sonic portraits of gla- Validating the EEDI methodology is a step toward ciers, which he calls sound casts, using field recordings standardized analyses in ecoacoustics, Farina says, to represent the whole geologic feature in a single † which can help ecologists judge habitat quality and piece (Audio S3 ). Glaciers are impressive sights, but landscape change. images don’t capture the slow-motion grinding, living Cases such as this illustrate the power of sound as quality of these dynamic rivers of ice, Burtner says. scientific data, but it does have limitations Farina says. Through their cracks, booms, trickles, and bellows, he For one, not all species vocalize or rely on their hear- hears glaciers come alive. ing. Some lean on other senses, such as sight, touch, To make his glacier sound casts, Burtner installs a and smell, to interpret their environment. Methods to variety of microphones and hydrophones over a glacier. collect acoustic data are also far from standardized, he Some sit on its snowy surface, others hang down into says, and metrics to extract information from audio crevasses, and still others rest in trickling meltwater files are also limited. streams. He uses rough-and-tumble microphones typ- Even so, sound naturally fosters interdisciplinary ical of geology research to pick up sounds in mud pits efforts such as Farina’s and Monacchi’sbydrawing and other low-gurgling, crunching places and hydro- artists to scientists who know the latest analytical phones suited for marine mammal research to catch techniques, says soundscape ecologist Bernie Krause. high frequencies. The medium, Farina adds, also draws scientists to Back in his studio, Burtner pipes his recordings artists, who often have better audio equipment through an array of speakers spread around the “ and better-honed communication skills. Our aim is room. He, like Monacchi, aims to capture the three- ” “ the same, he says, to collect information to inform dimensionality of sound. Burtner arranges the speak- ” people. ers so that a listener in a gallery or concert hall would “hear a crack of ice on your right and then hear it Sound Inspiration traverse the glacier and be on your left a millisecond Artists often strive to recreate soundscapes: to bring later,” he says. “You can hear the dynamics of the the experience of a rainforest or thundering ocean glacier unfolding.” into a concert hall, radio performance, or exhibition What emerges is an impression that even a moun- space. Evoking an artistic sense of faraway lands taineer couldn’t experience in person. Booms and sometimes involves warping and manipulating re- echoes of the entire glacier, recorded from its craggy cordings and playing them in combination with the peaks down into icy cracks where no hiker could go, original sound files. surround the listener simultaneously. Composer Hildegard Westerkamp’s piece Beneath the Forest Floor carries listeners into the extreme quiet of Vancouver Island’s old-growth forests. It begins † Audio credit: Matthew Burtner, from “Sound Cast of Matanuska — ’ with a low thumping sound a recording of a raven s Glacier” and “Threnody (Sikuigvik)” (BMI) from the album Glacier call, slowed down. Westerkamp captured it and many Music (Parma).

12582 | www.pnas.org/cgi/doi/10.1073/pnas.1908588116 McDermott Downloaded by guest on September 30, 2021 Sonic Collaboration At Sugarloaf Ridge State Park in Sonoma County, Often, artistic and scientific sound projects aren’tso near Krause’s longtime home in Northern California, different. Recording and editing sound files, whether he documented an encroaching quiet, coinciding with animal calls or the pops and thumps of a glacier, re- the state’s prolonged drought. Krause has been re- quire a complex knowledge of instrumentation and cording every spring at Sugarloaf Ridge since 1993, “ software, Monacchi says. For us, dealing with science and he documented the sounds of birds, insects, and ” was never that far away. other life dropping progressively from 2011, with a That was certainly the case for soundscape ecolo- sharp drop in vocalizations in 2015. gist Krause. Working as a professional studio musician Krause published the findings in an article, coauthored in the 1960s and 1970s, Krause played for pop artists with Farina, on sound as a way to study climate George Harrison, Van Morrison, and The Doors. Then in change impacts in 2016 (7). He and Farina are now 1970, he and Paul Beaver released the album In a Wild working on a second collaboration, with ecologist Sanctuary, which incorporated natural soundscapes. Jerome Sueur of the National Museum of Natural Thus began Krause’s journey to investigating natural History in Paris. Since California’shistoric16-year sounds. He made high-quality recordings of whole hab- drought ended in 2017, Krause is hopeful for the itats in his free time, intrigued by their acoustic structure. After finishing his doctorate in creative sound arts Sugarloaf site. Heavy spring rains have called it back in 1981, with a focus on bioacoustics, Krause devel- to sonic life, he says. oped his niche hypothesis: in healthy habitats, different Ecologists and artists converge around acoustics species vocalize in unique bandwidths, each occupying because they know sound reveals otherwise-hidden ’ their own acoustic territory (6). Krause found that these dramas about both the natural world and humans territorial boundaries tend to disappear in stressed relationship to it. Working together, colleagues environments. The collective sound of the habitat across disciplines can “use the power of science to becomes chaotic as the organisms still present vie understand phenomena,” Monacchi says. “And use for acoustic territory, searching for new, available the power of art to share phenomena with the broad frequencies or new times to hoot and titter. public.”

1 J. Sueur, A. Farina, Ecoacoustics: The ecological investigation and interpretation of environmental sound. Biosemiotics 8,493–502 (2015). 2 E. O. Wilson, The Diversity of Life (Harvard University Press, Cambridge, 1993). 3 A. Farina, S. H. Gage, Ecoacoustics: The Ecological Role of Sounds (Wiley, Hoboken, 2017). 4 A. Farina, N. Pieretti, P. Salutari, E. Tognari, A. Lombardi, The application of the acoustic complexity indices (ACI) to ecoacoustic event detection and identification (EEDI) modeling. Biosemiotics 9,227–246 (2016). 5 A. Gasc et al., Soundscapes reveal disturbance impacts: Biophonic response to wildfire in the Sonoran Desert Sky Islands. Landsc. Ecol. 33, 1399–1415 (2018). 6 B. L. Krause Bioacoustics, habitat ambience in ecological balance. Whole Earth Rev. 57 (1987). 7 B. Krause, A. Farina, Using ecoacoustic methods to survey the impacts of climate change on biodiversity. Biol. Conserv. 195,245– 254 (2016).

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