Mono
A single channel
Identical in both ears. The sound comes "from the device", with no localisation.
The sound that surrounds you
Binaural sound,
in a few words
When a bee flies past the back of your neck, you know where it is without seeing it. Your two ears don't receive quite the same sound: it arrives a fraction of a millisecond earlier on one side, a little louder, and slightly coloured by the shape of your head and ears. Your brain compares these differences and works out a position in space.
Binaural sound means recreating those cues by computation. You start from ordinary sound sources, assign each one a position in space, then a process simulates what each ear would have heard from that spot. The result fits on two channels, but your brain reads them as a three-dimensional scene: in front, behind, overhead, right against your ear.
The three cases, side by side
Stereo
Two channels, a line
Sources are spread further left or further right. The sound image stretches along a line, in front of you.
Binaural
Two channels, a sphere
Two channels as well, but carrying the timing and timbre cues created by a human head. The image becomes a sphere that surrounds you.
One condition: you need headphones or earphones. On speakers, the effect collapses.
An example to listen to
Close your eyes, put the headphones on
A real binaural recording. Listen with headphones: the sounds settle around you, not between your two ears.
Binaural recording · headphones recommended
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Binaural recording, Creative Commons BY-SA 3.0 licence — archive.org . More royalty-free clips: pixabay.com .
This file comes from a real recording rather than computed spatialisation: the perceived effect is the same as Écoute moi voir ça's.
That's the whole EMVC experience
Out in the street, these voices play by themselves, in binaural sound, exactly where the stories were lived. The screen stays in your pocket.