A system for improving a spatial effect of stereo sound or encoded sound when producing three dimensional image sound signals from signals of stereo channel includes a spatial effect enhancing portion where a signal for enhancing spatial effect and directivity of sound is produced, a band enhancing portion...http://www.google.de/patents/US6587565?utm_source=gb-gplus-sharePatent US6587565 - System for improving a spatial effect of stereo sound or encoded sound
