Patent ID: 7171002
Filing Date: 2007-01-30
Classification: H04S

Abstract:
1. An expansion circuit for increasing an apparent stereo width produced by a left channel signal and a right channel signal, comprising: a left channel circuit operable to (i) substantially cancel energy at at least some frequencies from among a first range of frequencies of the left channel signal; (ii) produce an inverted left channel signal containing a band of frequencies from among a second range of frequencies; and (iii) produce a left channel high pass signal from the left channel signal containing frequencies from among those at or above a first corner frequency; and a right channel circuit operable to (i) substantially cancel energy at at least some frequencies from among the second range of frequencies of the right channel signal; (ii) produce an inverted right channel signal containing a band of frequencies from among the first range of frequencies; (iii) produce a right channel high pass signal from the right channel signal containing frequencies from among those at or above a second corner frequency, wherein: the left channel circuit further includes a left channel summation circuit operable to adjustably sum at least the left channel high pass signal and the inverted right channel signal, to produce a left channel expansion signal, and to sum at least the left channel signal and the left channel expansion signal to produce at least a portion of a left channel output signal; and the right channel circuit further includes a right channel summation circuit operable to adjustably sum at least the right channel high pass signal and the inverted left channel signal, to produce a right channel expansion signal, and to sum at least the right channel signal and the right channel expansion signal to produce at least a portion of a right channel output signal.