Patent ID: 7660424

Claim:
A process for translating M audio input signals, each associated with a direction, to N audio output signals, each associated with a direction, wherein N is larger than M, M is two or more and N is a positive integer equal to three or more, comprising; providing an M:N variable matrix, wherein the matrix is implemented by a digital signal processor, applying said M audio input signals to said variable matrix, deriving said N audio output signals from said variable matrix, and controlling said variable matrix in response to measures of (1) the relative levels of said input signals, and (2) the cross-correlation of said input signals so that a soundfield generated by said output signals has a compact sound image in the nominal ongoing primary direction of the input signals when the input signals are highly correlated, the image spreading from compact to broad as the correlation decreases and progressively splitting into multiple compact sound images, each in a direction associated with an input signal, as the correlation continues to decrease to highly uncorrelated, wherein for a measure of cross-correlation of the input signals having values in a first range, bounded by a maximum value and a reference value, the soundfield has a compact sound image when the measure of cross-correlation is said maximum value and has a broadly spread image when the measure of cross-correlation is said reference value, and for a measure of cross-correlation of the input signals having values in a second range, bounded by said reference value and a minimum value, the soundfield has said broadly spread image when the measure of cross-correlation is said reference value and has a plurality of compact sound images, each in a direction associated with an input signal, when the measure of cross correlation is said minimum value.