Example 1: A method comprising: detecting sound via a microphone array of a first playback device and analyzing, via a first wake-word engine of the first playback device, the detected sound; transmitting data associated with the detected sound from the first playback device to a second playback device over a local area network; analyzing, via a second wake-word engine of the second playback device, the transmitted data associated with the detected sound; identifying that the detected sound contains either (i) a first wake word based on the analysis via the first wake-word engine or (ii) a second wake word based on the analysis via the second wake-word engine; and based on the identification, transmitting sound data corresponding to the detected sound over a wide area network to a remote computing device associated with a particular voice assistant service. Example 2: The method of Example 1, wherein the sound data further contains a voice utterance and the method further comprises receiving, via one of the first playback device and the second playback device, at least one message from the remote computing device, where the message includes a playback command based on the voice utterance. The method may further include playing back, via at least one of the first playback device and the second playback device, audio content based on the playback command. Example 3: The method of Example 1 or Example 2, wherein the identifying comprises identifying the second wake word (i) based on the transmitted data associated with the detected sound and (ii) without detecting the sound via the second playback device. Example 4: The method of any one of Examples 1 to 3, wherein the microphone array comprises a plurality of individual microphones and the first playback device comprises a voice processor configured to receive portions of the detected sound from respective ones of the individual microphones. In such embodiments, the method may comprise processing, via the voice processor, one or more of the portions of the detected sound to produce the data associated with the detected sound that is transmitted to the second playback device. Example 5: The method of any one of Examples 1 to 4, further comprising processing the one or more portions of the detected sound comprises processing fewer than all of the portions of the detected sound. Example 6: The method of any one of Examples 1 to 5, further comprising spatially processing, via the voice processor, the detected sound based on one or more of the portions of the detected sound. In such embodiments, analyzing the detected sound via the first wake-word engine comprises analyzing the spatially processed detected sound. Example 7: The method of any one of Examples 1 to 6, further comprising (a) playing back, via the first playback device, audio content; and (b) producing, via the first playback device, at least one reference signal based on the audio content, where the data associated with the detected sound that is transmitted to the second playback device comprises data that is based on the at least one reference signal.