Patent ID: 7099480
Filing Date: 2006-08-29
Classification: H04S

Abstract:
1. A multi-channel sound system comprising: input means for receiving input left and right front sound signals and input left and right rear sound signals; left and right front loudspeakers for reproducing sounds corresponding to said input left and right front sound signals; left and right rear loudspeakers for reproducing sounds corresponding to said input left and right rear sound signals; generating means, coupled to receive said input left and right front and rear sound signals, for generating left and right virtual sound signals; and means for combining the left and right virtual sound signals and the input left and right front sound signals, respectively, to form output left and right front sound signals for application to said left and right front loudspeakers, wherein said left and right front loudspeakers reproduce both said sounds corresponding to said input left and right front sound signals and left and right virtual sounds corresponding to said left and right virtual sound signals, and said left and right rear loudspeakers reproduce said input left and right rear sound signals, said generating means generates said left and right virtual sound signals such that the left and right virtual sounds emanating from said left and right front loudspeakers appear, to a listener, to originate from virtual left and right loudspeakers positioned in a region between 80 and 100 degrees with respect to the listener, wherein said generating means comprises: first combining means for combining said input left front sound signal with said input left rear sound signal; second combining means for combining said input right front sound signal with said input right rear sound signal; and a virtual filter coupled to said first and second combining means, said virtual filter forming said left and right virtual sound signals, and wherein said virtual filter comprises: a first input coupled to an output of said first combining means, and a second input coupled to an output of said second combining means; a first sixth-order filter and a second sixth-order filter coupled to said first and second inputs, respectively; a first combination circuit and a second combination circuit, each having a first input coupled to respective outputs of said first and second sixth-order filters, outputs of said first and second combination circuits carrying the left and right virtual sound signals; a third sixth-order filter and a fourth sixth-order filter coupled to said first and second inputs, respectively; and first and second delay circuits coupled, respectively, to said third and fourth sixth-order filters, respective outputs from said first and second delay circuits being coupled to respective second inputs of said second and first combination circuits, wherein said first and second sixth-order filters are different from said third and fourth sixth-order filters.