Voices that surround the listener
It is our goal with On a Theme of Hermes to give the impression of an immersive aural experience. Part of our technique for achieving this is to apply simple spatialisation to the audio 'modules' that are seeded in the GPS landscape.
A sound source heard in a space such as a simple room (see diagram below) emits sound energy in all directions. Surfaces in the room (walls, ceiling, furniture, etc) reflect the sound energy but they also absorb a little energy too. The air between source and listener absorbs sound energy too: when the listener is located far from a source, they will hear less of the direct sound and more of the reflected sound.
As I said before, the three voice artists were recorded statically - but with careful processing the illusion of three moving speakers can be created.