Patent ID: 6920223

Claim:
Method for deriving at least three audio output signals from two input audio signals, comprising deriving four audio signals from said two input audio signals, wherein the four audio signals are derived with a passive matrix that produces two pairs of audio signals in response to two audio signals, a first pair of derived audio signals representing directions lying on a first axis and a second pair of derived audio signals representing directions lying on a second axis, said first and second axes being substantially mutually orthogonal to each other, processing each of said pairs of derived audio signals to produce respective first and second pairs of intermediate audio signals wherein the magnitudes of the relative amplitudes of the audio signals in each pair of intermediate audio signals are urged toward equality, producing a first output signal representing a first direction lying on the axis of the pair of derived audio signals from which the first pair of intermediate signals are produced, said first output signal being produced at least by combining, with the same polarity, at least a component of each of said second pair of intermediate audio signals, producing a second output signal representing a second direction lying on the axis of the pair of derived audio signals from which the first pair of intermediate signals are produced, said second output signal being produced at least by combining, with the opposite polarity, at least a component of each of said second pair of intermediate audio signals, producing a third output signal representing a first direction lying on the axis of the pair of derived audio signals from which the second pair of intermediate signals are produced, said third output signal being produced at least by combining, with the same polarity or the opposite polarity, at least a component of each of said first pair of intermediate audio signals, and, optionally, producing a fourth output signal representing a second direction lying on the axis of said pair of derived audio signals from which the second pair of intermediate signals are produced, said third output signal being produced at least by combining, with the opposite polarity, if the third output signal is produced by combining with the same polarity, or at least by combining with the same polarity, if the third output signal is produced by combining with the opposite polarity, at least a component of each of said first pair of intermediate audio signals.