Audio spatialization and environment simulation

Abstract

Methods are disclosed for improving sound localization of the human ear. In some embodiments, the method may include creating virtual movement of a plurality of localized sources by applying a periodic function to one or more location parameters of a head related transfer function (HRTF).

The invention claimed is: 
     
       1. A method for improving sound localization of a listener, the method comprising:
 receiving a sound signal including a left-ear signal and a right-ear signal in a controller; 
 modifying the left-ear signal and the right-ear signal, the step of modifying comprising:
 applying a plurality of Infinite Impulse Response (IIR) filters to each of the left-ear signal and the right-ear signal, the filters being calculated based on each of a left head related transfer function (HRTF) and a right HRTF; 
 creating a plurality of virtual localized sources at a plurality of positions with distances away from the listener; and 
 vibrating the plurality of virtual localized sources by a spatial oscillator. 
 
 
     
     
       2. The method of  claim 1 , wherein each IIR filer is associated with a position at an angle of azimuth, elevation and distance relative to the listener. 
     
     
       3. The method of  claim 1 , further comprising embedding a watermark signal in the localized left-ear signal and the right-ear signal for indicating that the signals are altered. 
     
     
       4. The method of  claim 1 , the step of modifying comprising splitting each of the left-ear signal and the right-ear signal into a first frequency band and a second frequency band having lower frequencies than the first frequency band. 
     
     
       5. The method of  claim 4 , further comprising bypassing the left-ear and right-ear signal in the second frequency band. 
     
     
       6. The method of  claim 4  further comprising splitting each of the left-ear signal and the right-ear signal in the first frequency band into a center signal and a stereo edge signal. 
     
     
       7. The method of  claim 6  further comprising localizing the stereo edge signals of left-ear and right-ear signals in the first frequency band by convolving the plurality of filters in a time domain. 
     
     
       8. The method of  claim 6  further comprising bypassing the center signals in the first frequency band. 
     
     
       9. The method of  claim 4 , further comprising adjusting output gain independently for each of the edge signal in the first frequency band, center signal in the first frequency band, and the signal in the second frequency band. 
     
     
       10. The method of  claim 1 , the step of outputting a localized left-ear signal and a localized right-ear signal comprising delaying the localized right-ear signal and the localized left-ear signal by a period of time that is an inter-aural time difference (ITD) and mixing the localized signals and bypassed signals in the first frequency band with respective bypassed signals in the second frequency band. 
     
     
       11. The method of  claim 1 , further comprising repeating the step of applying a periodic function through the step of outputting a localized left-ear signal and a localized right-ear signal to reprocess the localized left-ear and right-ear signals. 
     
     
       12. The method of  claim 1 , the step of vibrating comprising utilizing a sine wave generator with a frequency variable and a depth variable to dynamically adjust the plurality of positions of the virtual localized sources. 
     
     
       13. The method of  claim 2 , wherein the periodic function is selected from a group consisting of sinusoidal wave, square wave, and triangular wave. 
     
     
       14. The method of  claim 3 , further comprising detecting if there is a watermark in the left-ear signal and the right-ear signal by a decoder, if the watermark is present, bypassing the left-ear signal and the right-ear signal and if the watermark is absent, continuing with the step of modifying the signals. 
     
     
       15. The method of  claim 1 , further comprising dynamically adjusting the positions of the plurality of virtual localized sources in a three dimensional space. 
     
     
       16. A method for improving sound localization of a listener, the method comprising:
 receiving a sound signal including a left-ear signal and a right-ear signal in a controller; and 
 modifying the left-ear signal and the right-ear signal, the step of modifying comprising:
 splitting each of the left-ear signal and the right-ear signal into a first frequency band and a second frequency band, the first frequency band having higher frequencies than the second frequency band; 
 applying a plurality of Infinite Impulse Response (IIR) filters to each of the left-ear signal and the right-ear signal in the first frequency band, the filters being calculated based on each of a left head related transfer function (HRTF) and a right HRTF; 
 bypassing each of the left-ear and right-ear signals in the second frequency band; 
 attenuating each of the left-ear signal and right-ear signal in the first band by a band equalizer; 
 reversing the polarity of the signals in the first frequency band; and 
 mixing the signals in the first frequency band with the respective bypassed signals in the second frequency band.