Apparatus for creating 3D audio imaging over headphones using binaural synthesis including elevation

• US 6,421,446 B1
• Filed: 12/11/1998
• Issued: 07/16/2002
• Est. Priority Date: 09/25/1996
• Status: Expired due to Fees

• Current Assignee: QSound Labs, Inc.
• Original Assignee: QSound Labs, Inc.
• Inventors: Williams, Simon, Cashion, Terry
• Primary Examiner(s): Lee, Ping
• Application Number:
  US09/210,036
• Time in Patent Office: 1,313 Days
• Field of Search: 381/1, 381/17, 381/18, 381/61, 381/63
• US Class Current: 381/17
• CPC Class Codes: H04S 1/005 For headphones

Abstract

The apparent location of sound signals as perceived by a person listening to the sound signals over headphones can be positioned or moved in azimuth, elevation and range by a range control block and a location control block. Several range control blocks and location control blocks can be provided depending on the number of input sound signals to be positioned or moved. All of the range and location control is provided by the range control blocks and location control blocks so that the resultant signals require only a fixed number of filters regardless of the number of input audio signals to provide the signal processing. Such signal processing resulting in accurate positioning and moving of the sound source is accomplished using front and back early reflection filters, left and right reverberation filters, front and back azimuth placement filters having a head related transfer function, and up and down elevation placement filters.

Claims

1. 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.

2. The method of claim 1 further comprising the steps of:

azimuth adjusting a first portion of said second 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 second 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 second input signal, said ranging dependent in part on the configuration of said room model, the output of said ranging step being two signals modeled on early reflections based on said room model;

summing said second modeled signal with the undelayed and unattenuated azimuthally adjusted signal and summing said first modeled signal with the delayed and attenuated azimuthally adjusted signal;

passing each said summed signal portion through a HRTF;

passing the delayed and attenuated elevation adjusted signal portion through a first elevation placement filter forming a first filtered signal and passing the undelayed and unattenuated 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 first filtered signal to create an input signal for presentation to said first input of said headphone set; and

further combining said summed undelayed unattenuated azimuthally adjusted signal with said second filtered signal to create an input signal for presentation to said second input of said headphone set.

3. The method of claim 1, wherein said first and second elevation placement filters are implemented using a finite impulse response filter.

4. The method of claim 1, wherein said first and second elevation placement filters are implemented using an infinite impulse response filter.

5. The method of claim 1, wherein said elevation adjusting step comprises the step of:

scaling an amount of signal that is adjusted in the elevation adjusting step.

6. The method of claim 5, further comprising the step of:

determining the respective portions of said undelayed and unattenuated elevation adjusted signal to be passed through a first elevation placement filter and the delayed and attenuated elevation adjusted signal to be passed through a second elevation placement filter.

7. The method of claim 6, further comprising the step of:

receiving a first and second amplitude value and a first and second time delay value from a controller based on a current azimuth parameter value.

8. The method of claim 7, wherein said first time delay value is used to provide a time delay at said first elevation placement filter, and said second time delay value is used to provide a time delay at said second elevation placement filter.

9. The method of claim 8, wherein said first amplitude value is used to determine the portion of said undelayed and unattenuated elevation adjusted signal to be passed through said first elevation placement filter, and said second amplitude value is used to determine the portion of said delayed and attenuated elevation adjusted signal to be passed through said second elevation placement filter.

10. The method of claim 9, further comprising the step of:

receiving a plurality of multiplier factors from said controller.

11. The method of claim 10, wherein at least one of said plurality of multiplier factors is used to further determine the amount of each said summed signal portion and each said elevation adjusted signal to be passed through said first and second elevation placement filters.

12. An apparatus for 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, comprising:

means for accepting first and second input signals from a signal source;

means for 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 means including;

means for 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;

means for 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;

means for 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 being two signals modeled on early reflections based on said room model;

means for summing said first modeled signal with the undelayed and unattenuated azimuthally adjusted signal and means for summing said second modeled signal with the delayed and attenuated azimuthally adjusted signal;

means for passing each said summed signal portion through a Head Related Transfer Function (HRTF);

means for passing the undelayed and unattenuated elevation adjusted signal portion through a first elevation placement filter forming a first filtered signal and means for passing the delayed and attenuated elevation adjusted signal portion through a second elevation placement filter forming a second filtered signal;

means for 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

means for 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.

13. The apparatus of claim 12 further comprising:

means for azimuth adjusting a first portion of said second input signal into at least two output signal portions, one signal portion being delayed and attenuated with respect to the other signal portion;

means for elevation adjusting a second portion of said second input signal into at least two elevation adjusted signal portions, one signal portion being delayed and attenuated with respect to the other signal portion;

means for ranging a third portion of said second input signal, said ranging dependent in part on the configuration of said room model, the output of said ranging being two signals modeled on early reflections based on said room model;

means for summing said second modeled signal with the undelayed and unattenuated azimuthally adjusted signal and means for summing said first modeled signal with the delayed and attenuated azimuthally adjusted signal;

means for passing each said summed signal portion through a HRTF;

means for passing the delayed and attenuated elevation adjusted signal portion through a first elevation placement filter forming a first filtered signal and means for passing the undelayed and unattenuated elevation adjusted signal portion through a second elevation placement filter forming a second filtered signal;

means for combining said summed delayed attenuated azimuthally adjusted signal with said first filtered signal to create an input signal for presentation to said first input of said headphone set; and

means for further combining said summed undelayed unattenuated azimuthally adjusted signal with said second filtered signal to create an input signal for presentation to said second input of said headphone set.

14. The apparatus of claim 12, wherein said elevation adjusting means comprises:

means for scaling an amount of signal that is adjusted by the elevation adjusting means.

15. The apparatus of claim 14, further comprising:

means for determining the respective portions of said undelayed and unattenuated elevation adjusted signal to be passed through a first elevation placement filter and the delayed and attenuated elevation adjusted signal to be passed through a second elevation placement filter.

16. The apparatus of claim 15, further comprising:

means for receiving a first and second amplitude value and a first and second time delay value from a controller based on a current azimuth parameter value.

17. The apparatus of claim 16, wherein said first time delay value is used to provide a time delay at said first elevation placement filter, and said second time delay value is used to provide a time delay at said second elevation placement filter.

18. The apparatus of claim 17, wherein said first amplitude value is used to determine the portion of said undelayed and unattenuated elevation adjusted signal to be passed through said first elevation placement filter, and said second amplitude value is used to determine the portion of said delayed and attenuated elevation adjusted signal to be passed through said second elevation placement filter.

19. The apparatus of claim 18, further comprising:

means for receiving a plurality of multiplier factors from said controller.

20. The apparatus of claim 19, wherein at least one of said plurality of multiplier factors is used to further determine the amount of each said summed signal portion a each said elevation adjusted signal to be passed through said first and second elevation placement filters.