Sound from All Directions
One distinctive difference from regular movies? The importance of directional sound. Real life hears in all directions and which is why sound in virtual reality is designed for 360, too. Ambisonics is a full-sphere surround sound format: in addition to the horizontal plane, it covers sound sources above and below the listener.
Unlike other multichannel surround formats, transmission channels (4-channel) do not carry speaker signals; they hold a sound-field facsimile called B-format that does not depend on a speaker and is decoded to the listener’s speaker setup. The four channels in B- format don’t address directly to individual speakers the way that 5.1 surround signal is channeled to six speakers. These four channels represent the complete 3-dimensional spherical sound field.
The producer can think about how the sound comes from the source instead of where the loudspeakers are located. It gives the listener significant flexibility regarding layout and numbers of speakers used for playback.
This is what makes ambisonics fall into the domain of audio engineers and why sound design and spatial sound projection is essential to VR.