Patent ID: 7280664

Claim:
A method for deriving at least three audio signals, each associated with a direction, from two input audio signals, comprising generating with a passive matrix in response to said two input audio signals a plurality of passive matrix audio signals including two pairs of passive matrix audio signals, a first pair of passive matrix audio signals representing directions lying on a first axis and a second pair of passive matrix audio signals representing directions lying on a second axis, said first and second axes being substantially at ninety degrees to each other, processing each of said pairs of passive matrix audio signals to derive a plurality of matrix coefficients therefrom, said processing including deriving a pair of intermediate signals [(1−gL)*Lt′ and (1−gR)*Rt′, (1−gF)*Ft and (1−gB)*Bt] from each pair of passive matrix audio signals, respectively, and urging each pair of intermediate signals toward equality in response to a respective error signal, and producing at least three output signals by matrix multiplying said two input signals by said matrix coefficients.