Transaural synthesis method for sound spatialization
A method of producing a spatialized stereo audio file from an original stereo audio file comprises creating a data base of impulse responses realized in at least one physical space divided into left, right, front, back, up and down sides relative to a sound acquisition position, with at least one pair of acquisition microphones placed at the sound acquisition position, with at least two pairs of source loudspeakers placed at sound source positions; the sound acquisition position is situated at the left-right median plane of the physical space, the sound source positions are distributed symmetrically by pairs relative to the sound acquisition position, the data base of impulse responses comprising at least one left/right impulse response pair, the left and right impulse responses being obtained by a deconvolution of the direct acquired signal from all the source loudspeakers distributed at the respective left and right side of the physical space.
1. A method of producing a spatialized stereo audio file from an original stereo audio file, comprising:
creating a data base of impulse responses, wherein creating said impulse response is realised in at least one physical space, said physical space is divided into left and right sides, front and back sides, up and down sides relative to a sound acquisition position, with at least one pair of acquisition microphones placed at the sound acquisition position, with at least two pairs of source loudspeakers placed at a plurality of sound source positions;
wherein said sound acquisition position is situated at the left-right median plane of said physical space,
said sound source positions are distributed symmetrically by pairs relative to said sound acquisition position,
said data base of impulse responses comprising at least one impulse response pair of a left impulse response and a right impulse response,
the left impulse response being obtained by a deconvolution of a direct acquired signal from left source loudspeakers including all the source loudspeakers distributed at the left side of the physical space, wherein the direct acquired signal from the left source loudspeakers is based at least on a source signal applied at the same time to all the left source loudspeakers; and
the right impulse response being obtained by a deconvolution of the direct acquired signal from right source loudspeakers including all the source loudspeakers distributed at the right side of the physical space, wherein the direct acquired signal from the right source loudspeakers is based at least on the source signal applied at the same time to all the right source loudspeakers.
2. The method according to claim 1 , wherein a central loudspeaker is positioned at the sound source position situated at the left-right median plane and in front of the sound acquisition position, wherein the left impulse response is obtained by a deconvolution of the direct acquired signal from the left source loudspeakers and the central loudspeaker, wherein the right impulse response is obtained by a deconvolution of the direct acquired signal from the right source loudspeakers and the central loudspeaker.
3. The method according to claim 1 , wherein said sound source positions are distributed around a circle of 360° around said sound acquisition position, except an arc region of 30° behind the sound acquisition position (music mode).
4. The method according to claim 3 , wherein said sound source positions are distributed at the same height.
5. The method according to claim 1 , wherein said sound source positions are distributed in a sphere of 4pi around said sound acquisition position, except a region corresponding to 30° solid angle behind the sound acquisition position (cinema mode).
6. The method according to claim 5 , wherein each pair of sound source positions distributed symmetrically to the left-right median plan are at the same height, but not all pairs of sound source positions are at the same height.
7. The method according to claim 6 , wherein from front side to the back side, the height of each pair of sound source positions increases.
8. The method according to claim 1 , wherein the spatialized stereo audio file is realized by a treatment of convoluting the original stereo audio file with the said pair of left and right impulse response.
9. The method according to claim 8 , wherein the treatment is realized remotely on a server.
10. The method according to claim 8 , wherein the treatment is realized locally, on a local processor.
11. Utilization of the method according to claim 1 , wherein during a broadcast of the spatialized stereo audio file, a reproduced virtual sound source position is movable by tuning the power balance between the left and right broadcast channels.