Multi-channel spatialization system for audio signals
First Claim
1. A three dimensional audio display system for imposing selectively changeable spatial cues to a plurality of audio signals, comprising:
- a respective plurality of parallel audio signal paths for translating said plurality of audio signals and wherein each signal path includes,first filter means having a predetermined filter characteristic and being responsive to one audio signal of said plurality of audio signals,means coupled to said first filter means for converting said one audio signal to a digital audio signal,selectively changeable digital storage means coupled to said converting means and generating first and second digital audio signals in two discrete signal channels from said digital audio signal, each said channel further including means for storing time delay data and means for storing a set of filter coefficients derived from an arbitrary head related transfer function and implementing a synthetic head related transfer function in the form of a linear phase finite impulse response filter which operates to impose spatial cues to said first and second digital audio signals for a predetermined spatial location relative to a listener,means coupled to said digital storage means for converting said first and second digital audio signals to first and second analog audio signals,second filter means having a predetermined filter characteristic coupled to said converting means for filtering said first and second analog audio signals;
first and second circuit means coupled to said second filter means for combining respective first and second analog audio signals and generating therefrom first and second composite first and second audio signals; and
transducer means coupled to said first and second composite audio signals for generating a plurality of audio output signals which appear to emanate from selectively predetermined different spatial locations.
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Accused Products
Abstract
Synthetic head related transfer functions (HRTFs) for imposing reprogrammable spatial cues to a plurality of audio input signals included, for example, in multiple narrow-band audio communications signals received simultaneously are generated and stored in interchangeable programmable read only memories (PROMs) which store both head related transfer function impulse response data and source positional information for a plurality of desired virtual source locations. The analog inputs of the audio signals are filtered and converted to digital signals from which synthetic head related transfer functions are generated in the form of linear phase finite impulse response filters. The outputs of the impulse response filters are subsequently reconverted to analog signals, filtered, mixed and fed to a pair of headphones.
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Citations
20 Claims
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1. A three dimensional audio display system for imposing selectively changeable spatial cues to a plurality of audio signals, comprising:
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a respective plurality of parallel audio signal paths for translating said plurality of audio signals and wherein each signal path includes, first filter means having a predetermined filter characteristic and being responsive to one audio signal of said plurality of audio signals, means coupled to said first filter means for converting said one audio signal to a digital audio signal, selectively changeable digital storage means coupled to said converting means and generating first and second digital audio signals in two discrete signal channels from said digital audio signal, each said channel further including means for storing time delay data and means for storing a set of filter coefficients derived from an arbitrary head related transfer function and implementing a synthetic head related transfer function in the form of a linear phase finite impulse response filter which operates to impose spatial cues to said first and second digital audio signals for a predetermined spatial location relative to a listener, means coupled to said digital storage means for converting said first and second digital audio signals to first and second analog audio signals, second filter means having a predetermined filter characteristic coupled to said converting means for filtering said first and second analog audio signals; first and second circuit means coupled to said second filter means for combining respective first and second analog audio signals and generating therefrom first and second composite first and second audio signals; and transducer means coupled to said first and second composite audio signals for generating a plurality of audio output signals which appear to emanate from selectively predetermined different spatial locations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for producing a three dimensional audio display imposing selectively changeable spatial cues to a plurality of audio signals, comprising the steps of:
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feeding a plurality of analog audio signals outputted from a respective plurality of relatively narrow band audio signals coupled to a respective plurality of parallel signal paths; lowpass filtering said plurality of analog audio signals; converting said plurality of analog audio signals to digital audio signals; converting each of said digital audio signals to first and second digital audio channel signals; selectively delaying and filtering said first and second digital channel signals by feeding said digital audio channel signals to respective interchangeable circuit means, said circuit means implementing a predetermined time delay and a linear phase finite impulse filter response derived from a synthetic head related transfer function, thereby imposing spatial cues to said first and second digital audio channel signals for a desired spatial location relative to a listener; converting said digital audio channel signals to first and second analog audio channel signals; lowpass filtering said first and second analog audio channel signals; combining respective first and second analog audio channel signals and generating first and second composite first and second audio signals; and coupling said first and second composite second audio signals to transducer means, said transducer means reproducing a plurality of analog audio output signals which appear to emanate from different selectively changeable spatial locations. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification