Methods and apparatus for detecting a voice command

A mobile device, comprising:

• a first microphone;
• a second microphone;
• a primary processor;
• and
• a secondary processor programmed to:
• responsive to receiving, via a first microphone, an acoustic input while a primary processor and a second microphone are inactive, compare the acoustic input with a threshold, and responsive to detecting the acoustic input exceeds the threshold, instruct the second microphone to activate while the primary processor is still inactive,
• wherein the primary processor is programmed to:
• detect a voice command in the acoustic input based on at least one contextual cue without using a trigger word.

A non-transitory computer readable medium encoded with instructions that, when executed on at least one processor, perform a method of monitoring an acoustic environment of a mobile device to receive acoustic input in multiple stages including in a low power stage and normal power stage, the method comprising:

• receiving, via a first microphone, an acoustic input in the low power stage while a primary processor and a second microphone are inactive and a secondary processor is active;
• processing, in the lower power stage, the acoustic input to determine whether the acoustic input relates to a spurious acoustic activity;
• responsive to the acoustic input not relating the spurious acoustic activity, activating the primary processor to enter into the normal power stage;
• and
• processing, in the normal power stage, the acoustic input to detect a voice command based on at least one contextual cue without using a trigger word.