27. The system of claim 1 , wherein the executable instructions to close the audio signal stream from the client device comprise executable instructions to at least: close a connection with the client device, reject audio data from the client device, or instruct the client device to stop transmitting audio data.
1. A system comprising: a computer-readable memory storing executable instructions; and one or more processors in communication with the computer-readable memory, wherein the one or more processors are programmed by the executable instructions to at least: obtain from a client device: an audio signal, wherein a first portion of the audio signal comprises audio data likely corresponding to a wake word, and wherein a second portion of the audio signal does not comprise audio data likely corresponding to the wake word; contextual information associated with the audio signal; and information indicating the first portion of the audio signal comprises audio data likely corresponding to the wake word; obtain acoustic information and environmental information from the first portion of the audio signal, wherein the acoustic information reflects one or more characteristics of a voice in the audio signal, and wherein the environmental information reflects one or more characteristics of an environment in which sound in the audio signal was recorded; determine whether audio data corresponding to the wake word is present in the audio signal using a server-side detection model configured to generate a detection score using the contextual information, the environmental information, the acoustic information, and natural language understanding results generated based at least partly on at least one of the audio signal or a subsequent audio signal, wherein a detection score greater than a detection threshold indicates that audio data corresponding to the wake word is present in the audio signal; in response to determining that audio data corresponding to the wake word is present in the audio signal, perform an action corresponding to a request in the audio signal; and in response to determining that audio data corresponding to the wake word is not present in the audio signal, close an audio signal stream from the client device.