Method and apparatus for spatially enhancing stereo and monophonic signals

A method for enhancing an input signal comprising first and second input channels to produce a spatially enhanced output signal comprising first and second output channels, said method comprising the steps of:

• generating a sum signal in response to said first and second input channels;
• generating a difference signal in response to said first and second input channels;
• enhancing said sum signal using a first filter to produce an enhanced sum signal;
• summing said enhanced sum signal and said difference signal to produce a first intermediate signal;
• enhancing said first intermediate signal using a second filter to produce a second intermediate signal;
• summing said second intermediate signal with said sum signal to produce said first output channel;
• and
• subtracting said second intermediate signal from said sum signal to produce said second output channel.

A method for spatially enhancing an audio signal having first and second channels wherein said audio signal is either a monophonic signal or a stereo signal, said method comprising the steps of:

• (a) combining said first and second channels of said audio signal to produce sum and difference signals;
• (b) processing said sum signal to produce an enhanced sum signal;
• (c) combining said enhanced sum signal and said difference signal to produce an intermediate signal;
• and
• (d) combining said intermediate signal with said audio signal to produce a spatially enhanced audio signal.

A method for spatially enhancing an audio signal having first and second channels wherein said audio signal is either a monophonic signal or a stereo signal, said method comprising the steps of:

• (a) combining said first and second channels of said audio signal to produce sum and difference signals;
• (b) processing said sum signal to produce an enhanced sum signal;
• (c) combining said enhanced sum signal and said difference signal to produce a first intermediate signal;
• (d) processing said intermediate signal to produce an enhanced first intermediate signal;
• (e) combining said first intermediate signal and said first enhanced intermediate signal to produce a second intermediate signal;
• and
• (f) combining said second intermediate signal with said audio signal to produce a spatially enhanced audio signal.

A method for spatially enhancing an audio signal having first and second channels wherein said audio signal is either a monophonic signal or a stereo signal, said method comprising the steps of:

• (a) combining said first and second channels of said audio signal to a produce a sum signal;
• (b) processing said sum signal to produce an enhanced sum signal;
• (c) combining said enhanced sum signal with said first and second channels of said audio signal to produce first and second intermediate signals, respectively;
• (d) combining said first and second intermediate signals to produce a first channel of a spatially enhanced audio signal;
• and
• (e) combining said first channel of said spatially enhanced audio signal with said audio signal to produce a second channel of said spatially enhanced audio signal.

A method for spatially enhancing an audio signal having first and second channels wherein said audio signal is either a monophonic signal or a stereo signal, said method comprising the steps of:

• (a) combining said first and second channels of said audio signal to a produce a sum signal;
• (b) processing said sum signal to produce an enhanced sum signal;
• (c) combining said enhanced sum signal with said first channel of said audio signal to produce an intermediate signal;
• (d) combining said intermediate signal with said second channel of said audio signal to produce a first channel of a spatially enhanced audio signal;
• and
• (e) combining said first channel of said spatially enhanced audio signal with said first and second channels of said audio signal to produce a second channel of said spatially enhanced audio signal.

A system for spatially enhancing an audio signal having first and second channels, said audio signal being either a monophonic signal or a stereo signal, said system comprising:

• means for summing said first and second channels of said audio signal to produce a sum signal;
• means for processing said sum signal to produce an enhanced sum signal;
• means for combining said enhanced sum signal with said first and second channels of said audio signal to produce first and second intermediate signals, respectively;
• means for combining said first and second intermediate signals to produce a first channel of a spatially enhanced audio signal;
• and
• means for combining said first and second channels of said audio signal with said first channel of said spatially enhanced audio signal to produce a second channel of said spatially enhanced audio signal.