Methods and apparatus for detecting a voice command

1. A mobile device comprising:

at least one input configured to receive acoustic input from the environment of the mobile device while the mobile device is operating in a low power mode; and

at least one processor configured to:

detect whether the acoustic input includes a voice command from a user without requiring receipt of an explicit trigger from the user; and

execute the detected voice command while the mobile device is operating in the low power mode.

2. The mobile device of claim 1 , wherein the at least one processor is configured to perform a plurality of processing stages on the acoustic input to evaluate whether the acoustic input includes the voice command or corresponds to spurious acoustic activity.

3. The mobile device of claim 2 , wherein the at least one processor is configured to:

discontinue further processing of the acoustic input if a given processing stage of the plurality of processing stages determines that the acoustic input resulted from spurious acoustic activity;

initiate responding to the voice command if the given processing stage determines that the acoustic input includes a voice command; and

process the acoustic input in a subsequent processing stage selected from the plurality of processing stages if the given processing stage cannot conclude whether the acoustic input includes a voice command.

4. The mobile device of claim 2 , wherein performing the plurality of processing stages includes performing at least one voice activity detection processing stage.

5. The mobile device of claim 4 , wherein performing the at least one voice activity detection processing stage comprises performing spectral analysis on the acoustic input to evaluate whether a spectrum of the acoustic input is indicative of voice activity, performing periodicity analysis to evaluate whether signal periodicity of the acoustic input is indicative of voice activity and/or using phone loops to evaluate whether the acoustic input includes speech.

6. The mobile device of claim 2 , wherein performing at least one of the plurality of processing stages comprises performing at least one biometric analysis on the acoustic input to evaluate whether the acoustic input was received from the user of the mobile device.

7. The mobile device of claim 2 , wherein performing the plurality of processing stages comprises performing at least one speech processing stage.

8. The mobile device of claim 7 , wherein performing the at least one speech processing stage comprises performing limited vocabulary automatic speech recognition on the acoustic input, performing classification of the acoustic input including applying one or more statistical classifiers to evaluate whether the recognized speech is characteristic of a voice command and/or performing at least one natural language processing stage.

9. The mobile device of claim 2 , wherein performing at least one of the plurality of processing stages comprises evaluating at least one contextual cue selected from a group consisting of: time of day, motion of the mobile device, location of the mobile device, an occurrence of an event on the mobile device, recent activity on the mobile device and state of a battery powering the mobile device.

10. The mobile device of claim 2 , wherein the at least one processor is configured to:

provide an indication of confidence that the acoustic input includes a voice command based on performing at least one of the plurality of processing stages; and

select a subsequent processing stage to next process the acoustic input based, at least in part, on the indication of confidence from the at least one of the plurality of processing stages.

11. The mobile device of claim 1 , wherein the at least one processor is configured to provide a low-power indication that the voice command was detected.

12. The mobile device of claim 1 , wherein the at least one processor is configured to execute the detected voice command without waking up the mobile device.

13. The mobile device of claim 1 , wherein the mobile device is capable of connecting to at least one server via a network, and wherein the at least one processor is configured to transmit at least a portion of the acoustic input to the at least one server via the network for processing by the at least one server.

14. At least one non-transitory computer readable medium encoded with instructions that, when executed by at least one processor, cause a mobile device to perform a method comprising:

detecting whether acoustic input received from the environment of the mobile device while the mobile device is operating in a low power mode includes a voice command from a user without requiring receipt of an explicit trigger from the user; and

executing the detected voice command without waking up the mobile device.

15. The at least one non-transitory computer readable medium of claim 14 , further comprising instructions that, when executed by at least one processor, perform providing a low-power indication that voice activity was detected.

16. The at least one computer readable medium of claim 15 , further comprising performing a plurality of processing stages on the acoustic input to evaluate whether the acoustic input includes the voice command or corresponds to spurious acoustic activity.

17. The at least one non-transitory computer readable medium of claim 16 , further comprising instructions that, when executed by at least one processor, perform:

discontinuing further processing of the acoustic input if a given processing stage of the plurality of processing stages determines that the acoustic input resulted from spurious acoustic activity;

initiating responding to the voice command if the given processing stage determines that the acoustic input includes a voice command; and

processing the acoustic input in a subsequent processing stage selected from the plurality of processing stages if the given processing stage cannot conclude whether the acoustic input includes a voice command.

18. The at least one computer readable medium of claim 16 , further comprising instructions that, when executed by at least one processor, perform:

providing an indication of confidence that the acoustic input includes a voice command based on performing at least one of the plurality of processing stages; and

selecting a subsequent processing stage to next process the acoustic input based, at least in part, on the indication of confidence from the at least one of the plurality of processing stages.