3. The audio device of claim 1 , wherein the expression detector is further configured to determine that the trigger expression has been uttered by the user if the trigger expression occurs in the audio from multiple directions that are within two cone shapes extending from apexes at the audio device.
1. An audio device configured to respond to a trigger expression uttered by a user, comprising: a speaker configured to generate output audio; a microphone array configured to produce a plurality of input audio signals; an audio beamformer configured to produce a plurality of directional audio signals based at least in part on the input audio signals, wherein the directional audio signals represent audio from respectively corresponding directions relative to the audio device; one or more speech recognition components configured to detect that the trigger expression occurs in the audio represented by each of the respective directional audio signals; and an expression detector configured to: identify two or more directional audio signals, of the plurality of directional audio signals, that each include the trigger expression, determine that a total number of the two or more directional audio signals is less than a threshold number, in response to determining that the total number of the two or more directional audio signals is less than the threshold number, determine that the occurrence of the trigger expression in the audio is a result of an utterance of the trigger expression by a user, and based at least in part on determining that the occurrence of the trigger expression in the audio is a result of an utterance of the trigger expression by the user, provide a wake notification corresponding to the trigger expression to at least one processor of the audio device to change a state of the audio device.