Back to results
US 5,594,800 AGranted
Sound reproduction system having a matrix converter
AssigneeTrifield Productions Limited
InventorMichael A. Gerzon
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeTrifield Productions Limited
InventorMichael A. Gerzon
Estimating the term…
Matrix reproduction decoding means derive from input signals intended to feed a stereophonic plurality of loudspeakers output signals intended to feed a second greater plurality of loudspeakers in a stereophonic arrangement covering a sector of directions, substantially so as to preserve total reproduced energy to within an overall gain and equalization, and to preserve to within constants of proportionality the angular dispositions of reproduced acoustical velocity and sound intensity vectors at an ideal listening position. Preferably for two-channel signals matrix means is frequency-dependent giving increased angular width above 5 kHz, and may incorporate width control. Matrix means encoding loudspeaker feed signals into transmission channel signals, and matrix means decoding transmission channel signals into loudspeaker feed signals may be used giving overall matrix means in accordance with the invention. Matrix means may be used to provide improved directional matching of sounds and associated visual images.
A matrix converter R.sub.n2,n1 for converting a first audio signal (20) stereophonically encoded for reproduction over n.sub.1 speakers into a second audio signal (40) stereophonically encoded for reproduction over n.sub.2 loudspeakers, when n.sub.1, n.sub.2 are integers n.sub.1 >2 and n.sub.2 >n.sub.1, characterised in that the matrix converter R is an energy preserving matrix arranged substantially to preserve to within an overall constant of proportionality, the total reproduced energy and the reproduced directional effect of the encoded audio signal.
A matrix reproduction decoding means responsive to a first plurality of signals proportional to signals intended for reproduction via a first plurality of loudspeakers disposed in a first left/right symmetric stereophonic arrangement and providing a greater second plurality of signals proportional to signals intended for reproduction via a second plurality of loudspeakers disposed in a second left/right symmetric stereophonic arrangement said matrix decoder means comprising an input sum and difference matrix means for each pair of signals intended for a left/right symmetrically disposed pair of loudspeakers in said first arrangement, a first linear or matrix means responsive to all said sum signals and to any of said first plurality of signals proportional to a central loudspeaker feed signal for said first arrangement providing a first number not less than the number of signals into said first linear or matrix means of first output signals, a second linear or matrix means responsive to all said difference signals providing a second number not less than the number of said difference signals of output difference signals, said first number and said second number adding up to said second plurality, and output sum and difference matrix means, one associated with each left/right symmetric pair of loudspeakers in said second arrangement, each responsive to one of said first output signals and one of said output difference signals and providing signals from said second plurality of signals intended for said associated pair of loudspeakers in said second arrangement, whereby any of said second plurality of signals proportional to a central loudspeaker feed signal for said second arrangement is derived from one output of said first linear or matrix means.
A conversion matrix for converting a first ambisonically encoded audio signal having components W, X and Y or linear combinations thereof into a second, stereophonically encoded signal for reproduction over n.sub.2 loudspeakers, wherein n.sub.2 is an integer .ltoreq.3, the conversion matrix comprising a n.sub.2 .times.2 conversion matrix means for converting said first audio signal characterized in that the conversion matrix means is an energy preserving matrix arranged substantially to preserve to within an overall constant of proportionality the total reproduced energy and the reproduced directional effect of the encoded audio signal, said conversion matrix means arranged to receive at one input a first signal M.sub.dec formed from the sum of the omnidirectional component W and a first velocity component X and at the other input a signal S.sub.dec formed from the other velocity component Y and means for outputting a further signal component derived from the difference T.sub.dec of the said components W and X.
An audio transmission/reproduction system including in series a plurality of conversion matrices R.sub.ji for converting an input audio signal encoded for reproduction over i loudspeakers into an output audio signal encoded for reproduction over j loudspeakers, where i,j are integers and at least one of i,j is .ltoreq.3 for one or more of the conversion matrices, wherein the conversion matrices form a cascadable hierarchy in which for any two matrices R.sub.n3n2, R.sub.n2n1 the following conditions are satisfied:
An audio transmission/reproduction system including in series a plurality of conversion matrices R.sub.ji for converting a first signal directionally encoded for transmission/reproduction via a first number n.sub.i of channels into a second signal directionally encoded for reproduction via a second number n.sub.j of channels in which at least one of n.sub.i, n.sub.j is .gtoreq.3 and in which the matrices are elements of a cascadable hierarchy, at least one of the directionally encoded signals being for a reproduction format whose directional encoding does not have mathematical rotational symmetry.
A decoder for use in a frontal and rear stage stereo transmission/reproduction hierarchy including a conversion matrix formed as the inverse of a matrix including the stereo sum signal M which is formed from a forward facing combination of the directional component W and a velocity component X, the difference component S which is proportional to the side ways component Y, and the rear mono signal B which is formed from a backwards-facing combination of W and X and arranged to derive from stereo channels a B format signal for reproduction in an ambisonic or surround sound or frontal/rear stage stereo system.
A matrix converter R.sub.n2,n1 for converting a first audio signal stereophonically encoded for reproduction over n.sub.1 speakers into a second audio signal stereophonically encoded for reproduction over n.sub.2 loudspeakers, when n=2 and n.sub.2 is an integer>n.sub.1, characterized in that the matrix converter R is a frequency dependent energy preserving matrix arranged substantially to preserve to within an overall constant of proportionality the total reproduced energy and the reproduced directional effect of the encoded audio signal.
Dependencies are inferred from the claim text.