Patent ID: 7634092

Claim:
A method comprising: accepting a pair of audio input signals for audio reproduction; shuffling the input signals to create a first signal (“sum signal”) proportional to the sum of the input signals and a second signal (“difference signal”) proportional to the difference of the input signals; filtering the sum signal through a filter that approximates twice a center head related transfer function (“HRTF”) for a listener listening to a virtual sound source at a center location; filtering the difference signal through a filter that approximates the difference between a near ear HRTF and a far ear HRTF for the listener listening to a pair of virtual speakers; and unshuffling the filtered sum signal and the filtered difference signal to create a first output signal proportional to the sum of the filtered sum and filtered difference signals and a second output signal proportional to the difference of the filtered sum and filtered difference signals, such that in the case that the pair of audio input signals includes a center panned signal component, the listener listening to the first and second output signals through headphones is provided with the sensation that the center panned signal component emanates from the virtual sound source at the center location.