In a quiet corner of San Francisco, nestled among the warehouses and old ship-building docks far from downtown, some artists have constructed a temple of sound called Envelop.

On the surface, Envelop is just a room with a kickass surround sound system. Eight stacks of speakers are arranged along the walls, four towers on each side with four speakers inside each tower situated at different heights. There are also subwoofers in the corners and speakers in the ceiling. When the DJ cranks up a mellow dance track mixed especially for this system, sound waves rain down from above you, creep up from below you, spin around your head, and smother you in audio.

Envelop is a place designed for listening to music in a fully immersive, 360-degree environment. It's inside a larger arts complex called The Midway. They host events there, like yoga classes, ambient music performances, and EDM dance gatherings. There are listening parties coming up for Dark Side of the Moon and Geinoh Yamashirogumi's Akira Symphonic Suite. But Envelop is bigger than just a room full of speakers used for throwing events.

The group of artists who created Envelop also built the software tools to run it all. They've released their own plugin for the music creation app Ableton Live that lets musicians mix their songs not just in stereo, but all around the listener, in a full sphere. Any multi-speaker array can play back tracks mixed for Envelop, turning just about any room into a fully immersive audio playground.

Round and Around

Among sound designers, this technique of mixing in three dimensions is called ambisonics, or spatial audio.

"For years we've been listening to stereo, and that's incredible," says Envelop's executive director Christopher Willits. "However it's not composed to be moving around an audience. It's really just coming at you from one direction. So spatial audio allows a composer to use space as another part of that music. It allows an audience to have a shared experience of the sound. It's very similar to the way that we experience sound every day, which is in three dimensions all around us."

Spatial audio and ambisonics (the terms are interchangeable, at least outside of Reddit forums) have been around for a long time. You've watched a movie in multi-channel surround sound. You might even remember quadraphonic mixes of Santana and Isley Brothers LPs in the 1970s. But while those technologies can throw sound around a room in a horizontal plane, spatial audio involves mixing sound in a full sphere. That's trickier, and many of the tools currently available for creating spatial audio cost a pretty penny, or they're designed to only work with a specific company's microphones or mixing stations. There are, however, some great open-source software tools out there. Envelop is throwing itself in with that camp. The free Envelop plug-in currently works in Ableton Live, but Willits and his cohorts hope to develop code that works with other apps.

Willits says it's always been the core intention of the Envelop project to be open source and available to everyone. "We feel the idea of spatial audio has been wrapped up in a lot of proprietary methods, and that has withheld the ability for artists to afford the tools needed to create it. It's also kept the audience from experiencing the added value that spatial audio gives people."

Music of the Spheres

Added value indeed. Being in the audience for a spatial audio performance is really wild. Envelop at the Midway has 32 speakers around the room, and when you stand in the middle—or anywhere, really—you can feel sound filling the whole space. Drums spin around you, low drone notes buzz behind you, and high-frequency effects fizz and bubble on all sides. It's truly far out.