In the woods behind Wolf Trap’s temporarily idled amphitheater, the observant hiker can explore with ears as well as eyes: the ruffle of a bird in the underbrush, the splash of a turtle into Farm Pond, the flourish of a trumpet along a meandering stream.

The trumpet, of course, is not one of the customary sounds of springtime in the forest at Wolf Trap, the performing arts national park. The sounds of the horn and a dozen other instruments have been added by New York-based composer Ellen Reid, whose “Soundwalk” will be available free via digital devices (headphones recommended) throughout the spring and summer. It’s a means of bringing music back to the park without bringing people too close together.

The aural accompaniment to a Wolf Trap stroll is one of several versions of Reid’s real-life soundtrack, whose other editions can be heard in New York’s Central Park, Los Angeles’s Griffith Park and additional sylvan locations. Wolf Trap Foundation for the Performing Arts, the New York Philharmonic and several other groups co-commissioned the work.

The shimmering music is divided into discrete, varying-length pieces that Reid terms “cells,” each of which can be found only in a particular site. That doesn’t mean the cells are somehow literally there. Each mini-composition is geotagged to a specific place, in the manner of other sorts of virtual artworks that have become more prominent during the pandemic. The music actually dwells in the downloaded Soundwalk app, and emerges when a GPS-enabled cellphone or tablet comes in range.

The GPS is accurate to within 10 feet, so that different listeners in the same general area may have different musical experiences, Reid notes, via email. “The pace that you’re walking determines how the cells interact with each other,” the composer adds, and the “variation in location creates an element of chance. And nature adds an additional layer of chance to the listening experience.”

“Soundwalk’s” chimes, thrums and rhapsodies are gentle and sonorous, with hints of Richard Wagner, Erik Satie, Aaron Copland, Philip Glass and, naturally, ambient-music pioneer Brian Eno. The composition is less discordant, with fewer dynamic shifts, than Reid’s best-known work, “Prism,” an opera that won the 2019 Pulitzer Prize. To judge mostly from written descriptions, the Wolf Trap version may also be less assertive than the ones in New York and Los Angeles.

“The landscape of Wolf Trap called for a soundscape all its own,” Reid notes. “I made an effort to gesture toward the open spaces of the meadows, accentuate the curves of the trails, and amplify the excitement of the creeks that run through the trails at Wolf Trap.”

Wolf Trap’s rustic paths, known mostly to dog-walkers and birdwatchers, have fewer landmarks and historical associations than Central Park and Griffith Park — or, for that matter, D.C.’s National Mall, the locale of a Hirshhorn-sponsored audio walk devised by Janet Cardiff, one of Reid’s inspirations. (That was back in 2005, when smartphones were rare and the museum was obliged to loan iPods to people who wanted to follow Cardiff’s sonic itinerary.)

In the absence of well-established waypoints, Reid established her own, crafting “a layered listening experience at the benches that line the trails so a listener could sit for a longer period of time and listen,” she writes. She also hid a musical “Easter egg” inside the Filene Center, Wolf Trap’s main venue, a location that doesn’t appear on the “Soundwalk” map.

The appeal of the music aside, what’s most remarkable about the project is the way it fastens the virtual to the real. In a year when everything from trigonometry lessons to “Godzilla vs. Kong” is available on your phone, Reid’s composition might seem to be just another ripple in the digital tsunami. Yet every note is linked to a finite spot, so that the music and the scenery both require and complement each other. “Soundwalk” allows participants to stay in their virtual bubbles while insisting they engage with the physical world.

Ellen Reid: Soundwalk

Wolf Trap National Park for the Performing Arts, 1551 Trap Rd., Vienna.

Dates: Open sunrise to sunset seven days a week through Sept. 6.

Admission: Free; download the app at