5. A computer-implemented method comprising: as implemented by one or more computing devices configured to execute specific instructions, obtaining from a client device: audio input comprising a plurality of portions of audio data, wherein less than all of the plurality of portions of audio data comprise audio data corresponding to a keyword detected by the client device; contextual information associated with the audio input; and information indicating a portion of audio data, of the plurality of portions of the audio data, that likely corresponds to the keyword; obtaining acoustic information and environmental information from the portion of audio data that likely corresponds to the keyword; determining that the portion of audio data corresponds to the keyword using a detection model configured to generate a detection score using the audio input, the contextual information, the environmental information, and the acoustic information, wherein a detection score satisfying a detection threshold indicates audio data corresponding to the keyword is present in the audio input; and performing an action corresponding to a request in the audio input.
5. A computer-implemented method comprising: as implemented by one or more computing devices configured to execute specific instructions, obtaining from a client device: audio input comprising a plurality of portions of audio data, wherein less than all of the plurality of portions of audio data comprise audio data corresponding to a keyword detected by the client device; contextual information associated with the audio input; and information indicating a portion of audio data, of the plurality of portions of the audio data, that likely corresponds to the keyword; obtaining acoustic information and environmental information from the portion of audio data that likely corresponds to the keyword; determining that the portion of audio data corresponds to the keyword using a detection model configured to generate a detection score using the audio input, the contextual information, the environmental information, and the acoustic information, wherein a detection score satisfying a detection threshold indicates audio data corresponding to the keyword is present in the audio input; and performing an action corresponding to a request in the audio input. 26. The computer-implemented method of claim 5 , wherein determining whether the portion of the audio input corresponds to the keyword is based at least in part on the information regarding at least one of a start position or an end position of the portion of the audio input.