Patent ID: 7720237

Claim:
A method for minimizing the spectral deviations in the cross-over region of a combined bass-managed subwoofer-room and bass-managed satellite-room response, the method comprising: defining at least one second order all-pass filter having all-pass filter coefficients selectable to reduce incoherent addition of acoustic signals produced by the subwoofer and the satellite speaker; recursively computing the all-pass filter coefficients to minimize a phase response error, the phase response error being a function of phase responses of a subwoofer-room response, a satellite-room response, and the subwoofer and satellite bass-management filter responses; and cascading the all-pass filter with at least one of the satellite speaker bass-management filter and subwoofer bass-management filter; wherein computing the all-pass filter coefficients comprises: selecting initial values for pole angles and magnitudes; computing gradients ∇ ri and ∇ θi for pole angle and magnitude; multiplying the angle and magnitude gradients ∇ ri and ∇ θi times an error function J(n) and times adaptation rate control parameters μ r and μ θ to obtain increments; adding the increments to the pole angles and magnitudes to recursively compute new pole angles and magnitudes; randomizing the pole magnitude if the pole magnitude is <1; and testing to determine if the pole angle and magnitudes have converged, wherein if the if the pole angle and magnitudes have converged, the computing method is done, otherwise, the steps stating with computing gradients are repeated.