There are three primary types of sound in our environments. There is geophony, which is the sound made by geophysical forces like rain, snow, rivers, ice, and cobble stones; biophony, which is the “sound of life,” including birds, frogs, and other animals; and anthropony, which is the “sound we make” through air conditioners, trains, and cars that creates a “low hum, like the base drum of the world.” In every soundscape, one component of sound dominates: NYC is clearly defined by its anthropony, while the Brazilian rainforest is one of the purest expressions of biophony. Soundscapes are the acoustic representations of a place and can be conserved, enhanced, or actively managed.
According to Chris Streb, an ecological engineer with Biohabitats, who presented at the ASLA 2019 Conference on Landscape Architecture in San Diego, sound is also a “powerful component of placemaking.” Soundscapes can be analyzed, planned, and then designed.
“Our sense of hearing is often overlooked, but sound is critical. It’s our first sense in our mothers’ wombs — the sound of our mother’s voice.”
Humans can hear farther than they can see. Nature, in fact, privileges sound. “All higher vertebrate animals have hearing but not all have sight.” Without sound, many species, like birds, which rely on song to attract mates, wouldn’t be able to reproduce. Other species, like whales, even create “pop songs” that can go viral, spreading through their oceanic communities. “We think they create songs to impress their mates.” Predators rely on sound to capture prey, and prey use the same sense to evade being eaten.
In a world filled with Anthropogenic noise, “we are forgetting how to listen,” which is a shame because we can learn a great deal from hearing to the natural world. For example, if you listen carefully, you can tell the temperatures from the frequency of the chirps of the Snowy Tree Cricket (Oecanthus fultoni).
Through the noise we make, we are not only “interfering with our own experience of nature” but also nature’s ability to communicate. Frogs, for example, stop their chorus for up to 45 minutes after being disturbed by a “big noise.” Being silent for that long makes them more vulnerable to predators and also stops them from mating.
The health of an ecosystem can in part be determined by the sound it makes. The traditional method of analyzing the vitality of an ecosystem is to use jars and nets to capture fish, butterflies, birds, bats, and other critters. Another common approach is a Bioblitz in which a group of citizen scientists scour a given territory and count all species in a given time frame. The problem is these kinds of surveying are “very labor intensive, take lots of people, and also stressful on the animals themselves.”
Instead, a soundscape analysis conducted many times a day can be “worth a thousand pictures.” The depth and variety of sounds in an ecosystem can provide a metric for species density and diversity.
Streb showed a slide of an expanse of woods that had been recorded both before and after it was thinned out through logging. A base level was created to capture the sound of the stream and bird chatter, and then after the logging, recorded again. “The soundscape was totally different,” with a noticeable reduction in the amount of sound.
According to Lauren Mandel, ASLA, an associate and researcher at landscape architecture firm Andropogon Associates, “soundscape mapping” can help landscape architects maximize geophonic and biophonic sounds humans and animals naturally gravitate to and minimize the anthropogenic sounds that create a negative physiological response.
Working with Michael Mandel, an assistant professor at Brooklyn College, who brought deep expertise in how to apply digital tools to measure the quantity and quality of sounds, Andropogon mapped the sounds of the 6,800-acre Shield Ranch in Austin, Texas, as part of a master plan that determined areas of development and preservation. One goal was to protect the the most vital ecological soundscapes while allowing anthropogenic noise in areas that are already impacted by human sounds. Areas in red on the map had the largest amount of anthroponic noise.
Michael Mandel said measuring the sound along the river and amid canyons of the ranch was challenging, as “sound travels in waves and ripples through the air, and when sound waves encounter a solid object, they bounce off, echo.” On a mountain top, for example, the case is “if you can see something, you can hear it.” But in other areas where echoes happen, “there are things you can hear but can’t see.”
And at the 2,500-acre Avalon Park & Preserve in Stony Brook, Long Island, which includes a diverse range of landscapes such as forests and tidal marshes, Andropogon also created a soundscape map that not only helped plan and design a new 7-acre park within the landscape, but also schedule public events and educational programs.
After a BioBlitz that identified the number of species at Avalon, Andropogon and their team set up audio recording devices to measure the type and decibel levels of natural and human sounds throughout the site. With sound meters purchased on Amazon.com, they conducted three readings a day in different locations. Andropogon also brought in local middle school and elementary school students to help with sound measurements. Older kids used a checklist while younger ones had a “visually-oriented form with images instead of words,” said Lauren Mandel.
While capturing decibels is useful, “getting measurements of sound quality is much more valuable.” Breaking the site into zones, Andropogon discovered the most pleasant sounding spaces were near meadows and forests, while the least pleasant next to a road crossing. The analysis led them to put a large sculpture, which was initially planned for a space in the woods, an area with a very high sound quality, in a place with a low sound quality. Visiting the sculpture is an anthropogenic experience anyway and bringing high numbers of visitors into the woods would only degrade the sound quality there. Thoughtful efforts like these helped increase the biodiversity in Avalon by 35 percent.
Sound guided the program schedule for spaces, too. To avoid “sonic conflicts,” they didn’t organize yoga at the same time as lawn mowing or mechanical pruning. And they also scheduled programs for kids when birds were their at their noisiest. “We shifted the program based on sound.”
Mandel explained how urban soundscapes can also be managed. Designers can use buildings, walls, and trees to dampen sounds. Reducing urban noise in green spaces increases their habitat value. And audio recordings of birdsong can be added to spaces to help reduce the negative impacts of anthropogenic noise.
Soundscape mapping can be done at the very large scale as well. Artificial intelligence is being programmed to listen to thousands of hours of recordings of Caribou and migrating birds made across millions of square kilometers of Alaska in order to analyze the ecosystem impacts of climate change or oil and gas exploration. The same systems can also be used to measure the effectiveness of ecological restoration efforts, explained Michael Mandel.
Artificial intelligence is already helping sound become a more mainstream species identification tool. Birdnet uses machine learning to help users identify what bird they have heard.