When a wake-word engine spots a wake word in detected sound, the NMD may determine that a wake-word event (i.e., a “wake-word trigger”) has occurred, which indicates that the NMD has detected sound that includes a potential voice input. The occurrence of the wake-word event typically causes the NMD to perform additional processes involving the detected sound. In some implementations, these additional processes may include outputting an alert (e.g., an audible chime and/or a light indicator) indicating that a wake word has been identified and extracting detected-sound data from a buffer, among other possible additional processes. Extracting the detected sound may include reading out and packaging a stream of the detected-sound according to a particular format and transmitting the packaged sound-data to an appropriate VAS for interpretation.
In turn, the VAS corresponding to the wake word that was identified by the wake-word engine receives the transmitted sound data from the NMD over a communication network. A VAS traditionally takes the form of a remote service implemented using one or more cloud servers configured to process voice inputs (e.g., AMAZON's ALEXA, APPLE's SIRI, MICROSOFT's CORTANA, GOOGLE'S ASSISTANT, etc.). In some instances, certain components and functionality of the VAS may be distributed across local and remote devices. Additionally, or alternatively, a VAS may take the form of a local service implemented at an NMD or a media playback system comprising the NMD such that a voice input or certain types of voice input (e.g., rudimentary commands) are processed locally without intervention from a remote VAS.