Patent ID: 6421446
Filing Date: 2002-07-16
Classification: H04S

Abstract:
A method of providing a headphone set with sound signals such that a listener will perceive the sound as coming from a source outside of the listener's head, said method comprising the steps of:accepting first and second input signals from a signal source; processing each said first and second input signal so as to produce modified sound signals for presentation to the respective first and second inputs of a headphone set; said processing step including the steps of: azimuth adjusting a first portion of said first input signal into at least two output signal portions, one signal portion being delayed and attenuated with respect to the other signal portion; elevation adjusting a second portion of said first input signal into at least two elevation adjusted signal portions, one signal portion being delayed and attenuated with respect to the other signal portion; ranging a third portion of said first input signal, said ranging dependent in part on the configuration of a room model, the output of said ranging step being two signals modeled on early reflections based on said room model; summing said first modeled signal with the undelayed and unattenuated azimuthally adjusted signal and summing said second modeled signal with the delayed and attenuated azimuthally adjusted signal; passing each said summed signal portion through a Head Related Transfer Function (HRTF); passing the undelayed and unattenuated elevation adjusted signal portion through a first elevation placement filter forming a first filtered signal and passing the delayed and attenuated elevation adjusted signal portion through a second elevation placement filter forming a second filtered signal; combining said summed delayed attenuated azimuthally adjusted signal with said second filtered signal to create an input signal for presentation to said second input of said headphone set; and further combining said summed undelayed unattenuated azimuthally adjusted signal with said first filtered signal to create an input signal for presentation to said first input of said headphone set, wherein said listener of said headphone set will perceive said sound as coming from a source located outside the head of the listener in a three dimensional space with the head of the listener as a center of the sphere.