Patent ID: 7203320

Claim:
An apparatus, comprising: an expansion circuit for increasing an apparent stereo width produced by a left channel signal and a right channel signal, the expansion circuit including: a left channel circuit operable to cancel energy at at least some frequencies from among a first range of frequencies from the left channel signal to produce at least a portion of a left channel output signal, the at least some frequencies from among the first range of frequencies being derived from a right channel signal, the left channel circuit including a left channel band-pass filter having a center frequency at about a mid-frequency of a second range of frequencies, the left channel band-pass filter being operable to produce an inverted left channel signal containing a band of frequencies from among the second range of frequencies; and a right channel circuit operable to cancel energy at at least some frequencies from among the second range of frequencies from the right channel signal to produce at least a portion of the right channel output signal, the at least some frequencies from among the second range of frequencies being derived from the left channel signal, the right channel circuit including a right channel band-pass filter having a center frequency at about a mid-frequency of the first range of frequencies, the right channel band-pass filter being operable to produce an inverted right channel signal containing a band of frequencies from among the first range of frequencies, wherein: the left channel circuit further includes a left channel summation circuit operable to sum at least the left channel signal and the inverted right channel signal to produce at least a portion of the left channel output signal; and the right channel circuit further includes a right channel summation circuit operable to sum at least the right channel signal and the inverted left channel signal to produce at least a portion of the right channel output signal.