Multi-dimensional parametric audio system and method
View Patent ↗Systems and methods that use ultrasonic emitters for producing multi-dimensional parametric audio are provided. The systems and methods can be configured to determine HRTF filters for the left and right ears of a listener using an optical imaging system to scan a profile of a listener. Audio content may be encoded into a left and right channel for producing a three dimensional sound effect for the listener of the audio content by: processing the sound channel into left and right input channel signals; applying the HRTF filters and acoustic crosstalk cancellations filters to the left and right channel signals to generate output left and right channel signals; and modulating the left and right output channel signal frequencies onto an ultrasonic carrier.
1. A method of producing multi-dimensional parametric audio, comprising:
determining head-related transfer function (HRTF) filters for the left and right ears of a listener;
applying the HRTF filters to left and right input channel signals to generate adjusted left and adjusted right channel signals;
applying acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals to generate left output and right output channel signals;
modulating the left and right output channel signal frequencies onto an ultrasonic carrier; and
playing the modulated left and right output channel signals using a left ultrasonic emitter and a right ultrasonic emitter.
2. The method of claim 1 , wherein determining HRTF filters for the left and right ears of the listener comprises scanning the listener with an optical imaging system to determine a profile of the listener, wherein the profile of the listener comprises the head, pinna, and torso measurements of the listener.
3. The method of claim 2 , wherein determining HRTF filters for the left and right ears of the listener further comprises:
comparing the scanned profile of the user with a predetermined set of HRTF profiles, each profile comprising a predetermined range of head, pinna, and torso measurements; and
automatically selecting one of the predetermined set of HRTF profiles.
4. The method of claim 2 , wherein determining HRTF filters for the left and right ears of the listener further comprises:
playing a plurality of sound samples at a predetermined frequency;
recording the sound samples at a plurality of microphones, wherein the plurality of microphones are configured for placement in the listener's left and right ears during recording; and
recording the listener's position relative to the left and right ultrasonic emitters using the optical imaging system when each sound sample is recorded.
5. The method of claim 2 , wherein determining HRTF filters for the left and right ears of the listener further comprises:
playing a plurality of sound samples;
receiving input from the listener identifying the apparent location of each
received sound sample relative to the listener; and
recording the listener's position relative to the left and right ultrasonic emitters using the optical imaging system when each input is received.
6. The method of claim 1 , wherein applying acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals to generate left and right output channel signals comprises:
phase inverting the adjusted right channel signal and the adjusted left channel signal;
adding a delay to the phase-inverted adjusted right channel signal;
adding a delay to the phase-inverted adjusted left channel signal;
combining the adjusted left channel signal with the delayed phase-inverted adjusted right channel signal to generate the left output channel signal; and
combining the adjusted right channel signal with the delayed phase-inverted adjusted left channel signal to generate the right output channel signal.
7. The method of claim 6 , wherein applying acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals further comprises applying amplitude, phase, or frequency adjustments to at least one of the adjusted right channel signal and the adjusted left channel signal.
8. The method of claim 6 , wherein the HRTF filters are applied based on a desired spatial positioning of audio emitted by the left and right ultrasonic emitters.
9. The method of claim 1 , further comprising processing a sound channel into the left and right input channel signals.
10. The method of claim 9 , further comprising:
generating a plurality of left output and right output channel signal pairs for a corresponding plurality of sound channels;
combining the plurality of left output signals to generate a composite left output signal; and
combining the plurality of right output signals to generate a composite right output signal.
11. The method of claim 2 wherein the optical imaging system is an optical profilometer.
12. A multi-dimensional parametric audio system, comprising:
means for determining head-related transfer function (HRTF) filters for the left and right ears of a listener;
a parametric audio encoder configured to:
apply the HRTF filters to left and right input channel signals to generate adjusted left and adjusted right channel signals; and
apply acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals to generate left output and right output channel signals;
frequency modulating the left and right output channel signal frequencies onto an ultrasonic carrier; and
left and right ultrasonic emitters configured to play the modulated left output and right output channel signals.
13. The system of claim 12 , wherein the means for determining head-related transfer function (HRTF) filters for the left and right ears of the listener comprises an optical imaging system that scans the listener to determine a HRTF profile of the listener, wherein the HRTF profile of the listener comprises the head, pinna, and torso measurements of the listener.
14. The system of claim 13 , wherein the means for determining head-related transfer function (HRTF) filters for the left and right ears of the listener is further configured to:
play the scanned profile of the user with a predetermined set of HRTF profiles, each profile comprising a predetermined range of head, pinna, and torso measurements; and
automatically selecting one of the predetermined set of HRTF profiles.
15. The system of claim 13 , wherein the means for determining head-related transfer function (HRTF) filters for the left and right ears of the listener is further configured to:
play a plurality of sound samples at a predetermined frequency;
record the sound samples at a plurality of microphones, wherein the plurality of microphones are configured for placement in the listener's left and right ears during recording; and
record the listener's position relative to the left and right ultrasonic emitters using the optical imaging system when each sound sample is recorded.
16. The system of claim 13 , wherein the means for determining head-related transfer function (HRTF) filters for the left and right ears of the listener is further configured to:
play a plurality of sound samples at a predetermined frequency;
receive input from the listener identifying the apparent location of each received sound sample relative to the listener; and
record the listener's position relative to the left and right ultrasonic emitters using the optical imaging system when each input is received.
17. The system of claim 12 , wherein applying acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals to generate left and right output channel signals comprises:
phase inverting the adjusted right channel signal and the adjusted left channel signal;
adding a delay to the phase-inverted adjusted right channel signal;
adding a delay to the phase-inverted adjusted left channel signal;
combining the adjusted left channel signal with the delayed phase-inverted adjusted right channel signal to generate the left output channel signal; and
combining the adjusted right channel signal with the delayed phase-inverted adjusted left channel signal to generate the right output channel signal.
18. The system of claim 17 , wherein applying acoustic crosstalk cancellation filters to the adjusted left and adjusted right channel signals further comprises applying amplitude, phase, or frequency adjustments to at least one of the adjusted right channel signal and the adjusted left channel signal.
19. The system of claim 17 , wherein the HRTF filters are applied based on a desired spatial positioning of audio emitted by the left and right ultrasonic emitters.
20. The system of claim 12 , wherein the parametric audio encoder is further configured to:
receive an audio component corresponding to a sound channel; and
process the audio component into the left and right input channel signals.
21. The system of claim 20 , wherein the parametric audio encoder is further configured to:
generate a plurality of left and right output channel signals for a corresponding plurality of sound channels;
combine the plurality of left output signals to generate a composite left output signal; and
combine the plurality of right output signals to generate a composite right output signal.
22. The system of claim 13 , wherein the optical imaging system is an optical profilometer.