Surround sound apparatus
AssigneeTrifield Productions Limited
InventorsMichael Anthony Gerzon, Geoffrey James Barton
Life of this patent
Estimating the term…
Abstract
A surround sound apparatus wherein a decoder decodes directionally encoded audio signals for reproduction via a loudspeaker layout over a listening area wherein the signals are decoded by a matrix. The coefficients of the decoding matrix are such that at a predetermined listening position, the reproduced velocity vector direction and the reproduced energy vector position directions are substantially equal to each other and substantially independent of frequency in a broad audio frequency range The gain coefficients of the decoding matrix are such that the reproduced velocity vector magnitude varies systematically with encoded sound direction at frequencies in the region of and above a predetermined middle audio frequency.
Claims39
A decoder (2) for decoding directionally encoded audio signals for reproduction via a loudspeaker layout (4) over a listening area, comprising:
- an input (21) for receiving the directionally encoded audio signals;
- matrix means (22,23) for modifying said audio signals;
- and
- an output (24) for outputting the modified audio signal in a form suitable for reproduction via the loudspeakers;
- the coefficients of said matrix means being such that at a predetermined listening position in the listening area the reproduced velocity vector direction and the reproduced energy vector directions are substantially equal to each other and substantially independent of frequency in a broad audio frequency range,
- characterised in that the gain coefficients of said matrix means (22,23) are such that the reproduced velocity vector magnitude r.sub.v of a decoded audio signal varies continuously in a predetermined manner with encoded sound direction at frequencies in the region of and above a predetermined middle audio frequency.
An audio system comprising:
- a decoder;
- a multiplicity of loudspeakers laid out around a listening area;
- and
- an amplifier for amplifying the output of the decoder to drive the loudspeakers;
- the decoder decoding directionally encoded audio signals for reproduction via the loudspeaker layout over the listening area, the decoder comprising:
- an input for receiving the directionally encoded audio signals;
- matrix means for modifying said audio signals;
- and
- an output for outputting the modified audio signal in a form suitable for reproduction via the loudspeakers;
- the coefficients of said matrix means being such that at a predetermined listening position in the listening area the reproduced velocity vector direction and the reproduced energy vector directions are substantially equal to each other and substantially independent of frequency in a broad audio frequency range,
- characterised in that the gain coefficients of said matrix means are such that the reproduced velocity vector magnitude r.sub.v of a decoded audio signal varies substantially with encoded sound direction at frequencies in the region of and above a predetermined middle audio frequency.
A method of decoding directionally encoded audio signals for reproduction via a loudspeaker layout over a listening area, comprising applying the encoded audio signal to matrix means arranged to decode the signal, and
- outputting the signal in a form suitable for subsequent reproduction via the loudspeakers,
- the coefficient of said matrix means being such that at a predetermined listening position in the listening area the reproduced velocity vector direction and the reproduced energy vector direction are substantially equal to each other and substantially independent of frequency in a broad audio frequency range,
- characterised in that the reproduced velocity vector magnitude r.sub.v of a decoded audio signal varies continuously in a predetermined manner with encoded sound direction at frequencies in the region of and above a predetermined middle audio frequency.
A method according to 33, in which low audio frequencies of the encoded audio signal below a predetermined cross-over frequency are decoded by first matrix means, and high audio frequencies above the crossover frequency are decoded by second matrix means different in effect to the first matrix means, the broad audio frequency range in which the reproduced velocity vector direction and the reproduced energy vector direction are substantially equal to each other and substantially independent of frequency encompassing the cross-over frequency;
- and
- the reproduced velocity vector magnitude r.sub.v varying substantially with encoded sound direction at frequencies in the region of and above the cross-over frequency.
Dependencies are inferred from the claim text.