Switching binaural sound

1. A method comprising:

storing head-related transfer functions (HRTFs) in memory of a head mounted display (HMD) worn on a head of a user;

displaying, with a display of the HMD worn on the head of the user, a three-dimensional (3D) virtual environment that includes a virtual image;

processing, by a digital signal processor (DSP) in the HMD, sounds with the HRTFs to generate binaural sound that is provided to the user and that externally localizes in empty space to the virtual image in the 3D virtual environment;

sensing, with one or more sensors in the HMD, when the user leaves the 3D virtual environment that includes the virtual image; and

warning the user that the user is leaving the 3D virtual environment by filtering, by the DSP, the binaural sound to alter audio cues to prevent the user from experiencing external localization of the sounds and by lowering a volume of the sounds being provided to the user.

2. The method of claim 1 further comprising:

warning the user that the user is leaving the 3D virtual environment by removing, by the DSP, background sounds that occur in the 3D virtual environment as part of a game the user is playing.

3. The method of claim 1 , wherein the warning occurs when the user leaves a virtual room while remaining in the 3D virtual environment.

4. The method of claim 1 further comprising:

tracking, with head tracking in the HMD, head movements of the user; and

switching the sounds from the binaural sound to stereo sound when a face of the user is directed away from the virtual image.

5. The method of claim 1 further comprising:

switching the sounds from the binaural sound to stereo sound when the user activates a physical switch located in the HMD.

6. The method of claim 1 further comprising:

switching the sounds from the binaural sound to stereo sound when the virtual image vanishes in the 3D virtual environment.

7. A method executed by one or more electronic devices, the method comprising:

storing head-related transfer functions (HRTFs) in memory;

displaying, by a display of a wearable electronic device (WED) worn on a head of a user, a virtual image in an environment;

processing, by a digital signal processor (DSP), sounds with the HRTFs to generate binaural sound in empty space that is provided to the user and that externally localizes to the empty space and to the virtual image in the environment; and

determining, with the WED, when the user is leaving the environment; and

alerting the user that the user is leaving the environment by altering processing of the binaural sound to degrade audio cues in order to prevent the user from experiencing external localization of the binaural sound.

8. The method of claim 7 further comprising:

alerting the user that the user is leaving the environment by reducing a volume of the binaural sound being provided to the user.

9. The method of claim 7 further comprising:

displaying, by the WED, the virtual image while the user plays a game that includes a character as the virtual image; and

switching a voice of the character from the binaural sound to stereo sound when the character vanishes from the environment during the game.

10. The method of claim 7 further comprising:

alerting the user that the user is leaving the environment by switching the binaural sound to stereo sound.

11. The method of claim 7 further comprising:

switching the binaural sound to stereo sound upon activation of a switch on the WED.

12. The method of claim 7 further comprising:

wherein the WED includes electronic glasses, the environment is a physical room where the user is located, the virtual image is an augmented reality (AR) character that speaks to the user while the user plays a game, the WED includes head tracking, and a digital signal processor (DSP) in the WED reduces a volume of the binaural sound to alert the user when a face of the user is not directed to the virtual image in the environment.

13. The method of claim 7 further comprising:

sensing, with the WED, when a physical object interferes with a location of the virtual image in the environment; and

switching the binaural sound to stereo sound in response to sensing the physical object interferes with the location of the virtual image in the environment.

14. A method executed by one or more electronic devices, the method comprising:

storing head-related transfer functions (HRTFs) in memory;

displaying, with a wearable electronic device (WED) worn on a head of a user, a virtual image in an environment;

processing, by a digital signal processor (DSP), sound with the HRTFs to generate binaural sound that externally localizes in empty space from the virtual image in the environment;

determining, with the WED, when the user is leaving the environment; and

alerting the user that the user is leaving the environment by reducing a volume of the binaural sound that localizes from the virtual image and that is being provided to the user.

15. The method of claim 14 further comprising:

alerting the user that the user is leaving the environment by degrading the binaural sound being provided to the user as the user is leaving the environment.

16. The method of claim 14 further comprising:

alerting the user that the user is leaving the environment by altering, by the DSP, processing of the binaural sound so the user perceives less external localization.

17. The method of claim 14 further comprising:

alerting the user that the user is leaving the environment by removing interaural time differences (ITDs) of the binaural sound being provided to the user.

18. The method of claim 14 further comprising:

alerting the user that the user is leaving the environment by eliminating audio cues in the binaural sound being provided to the user.

19. The method of claim 14 further comprising:

alerting the user that the user is leaving the environment by switching the binaural sound playing to the user to stereo sound.

20. The method of claim 14 further comprising:

detecting, with a microphone in the WED, a voice of a person in the environment of the user; and

switching the binaural sound to stereo sound in response to detecting the voice.