Sound system and method of sound reproduction

Abstract

A sound reproduction system comprises a left and right speakers located in close proximity, and a sound processor which provides audio signals to the pair of speakers. The sound processor preferably derives a cancellation signal from the difference between the left and right channels. The resulting difference signal is scaled, delayed (if necessary), and spectrally modified before being added to the left channel and, in opposite polarity, to the right channel. The spectral modification to the difference channel preferably takes the form of a low-frequency boost over a specified frequency range, in order to restore the correct timbral balance after the differencing process. Additional phase-compensating all-pass networks may be inserted in the difference channel to correct for any extra phase shift contributed by the spectral modifying circuit. The technique may be used in a surround sound system.

1 . A sound reproduction system for a surround sound stereophonic system, comprising:
 a surround left speaker;   a surround right speaker;   a pair of surround back speakers located in close proximity and oriented in substantially the same direction, said surround back speakers comprising a surround back left speaker and a surround back right speaker;   a surround left channel audio signal electrically connected to said surround left speaker;   a surround right channel audio signal electrically connected to said surround right speaker; and   a sound processor receiving as inputs said left channel audio signal and said right channel audio signal, said sound processor configured to generate a difference signal representing a difference between said surround left channel audio signal and said surround right channel audio signal, apply spectral weighting to said difference signal thereby generating a spectrally weighted signal, and cross-cancel said spectrally weighted signal with said surround left channel audio signal and said surround right channel audio signal to respectively generate a surround back left speaker signal and a surround back right speaker signal for said surround back left and right speakers.