Example techniques relate to device spaces and default designations in a media playback system. A device space may create an association between a networked microphone device and one or more playback devices such that certain voice commands (e.g., playback commands) received by the networked microphone device are used to control the one or more playback devices (unless otherwise designated in the voice command). Furthermore, in bonded pairs and bonded groups of playback devices that include at least one NMD, certain playback devices within the bonded pair or group may be designated as default so as to avoid multiple responses to a voice input.

An example playback device is configured to (i) receive, via a network interface, data representing a command to play back audio content, where the audio content is a first type of audio content, (ii) during playback of the first type of audio content via an audio amplifier configured to drive a speaker, apply a first calibration and a second calibration to playback by the playback device, where the first calibration at least partially offsets one or more acoustic characteristics of an environment surrounding the playback device when applied to playback by the playback device, and where the second calibration corresponds to the first type of audio content, and (iii) during playback of a second type of audio content via the audio amplifier configured to drive the speaker, apply a third calibration to playback by the playback device, where the third calibration corresponds to the second type of audio content.

A signal processing apparatus includes: an obtaining portion configured to obtain an impulse response in a semi-open state in which, among a plurality of acoustic feedback systems, at least one acoustic feedback system is open and at least one acoustic feedback system is closed; and a calculating portion configured to calculate a gain correction amount based on the impulse response that the obtaining portion has obtained and to output a calculated gain correction amount.

A self diagnostic loudspeaker load impedance testing system, or Push Here Diagnostic (PHD) system, located within a mixer/amplifier for testing loudspeaker connections to the mixer amplifier during installation and maintenance. The system includes a test signal source that replaces the normal audio input to the amplifier during test. A PHD analyzer within the mixer amplifier analyzes the response of the loudspeakers and related wiring to the test signal to detect a total system impedance that exceeds the amplifier rating and to detect short circuits in the wiring. The PHD analyzer illuminates an indicator when a fault occurs. The test is initiated by depressing a momentary contact switch within the mixer amplifier housing by inserting a tool through an opening in the mixer amplifier housing.

A communication device includes a loudspeaker to transmit sound into a room. A signal having a white noise-like frequency spectrum spanning a frequency range of human hearing is generated. Auditory thresholds of human hearing for frequencies spanning the frequency range are stored. Respective levels of background noise in the room at the frequencies are determined. The white noise-like frequency spectrum is spectrally shaped to produce a shaped frequency spectrum having, for each frequency, a respective level that follows either the auditory threshold or the level of background noise at that frequency, whichever is greater. The shaped frequency spectrum is transmitted from the loudspeaker into the room.

A first playback device is configured to (i) place audio frames representative of audio content in a buffer, each frame including respective playback timing information identifying a time to play back the audio frame, (ii) transmit the audio frames in the buffer to a second playback device, (iii) receive a command to adjust playback of the audio content, (iv) based on the command, identify a range of audio frames previously transmitted, (v) select a new start time for the range of audio frames, (vi) cause the second playback device to update the playback timing information for each audio frame in the range based on the new start time, (vii) update, in the buffer, the playback timing information for each audio frame in the range based on the new start time, and (viii) play back the audio content in synchrony with the second playback device based on the updated playback timing information.

Example techniques may involve calibration with multiple recording devices. An implementation may include a mobile device receiving data indicating that a calibration sequence for multiple playback devices has been initiated in a venue. The mobile device displays a prompt to include the first mobile device in the calibration sequence for the multiple playback devices and a particular selectable control that, when selected, includes the first mobile device in the calibration sequence. During the calibration sequence, the mobile device records calibration audio as played back by the multiple playback devices and transmits data representing the recorded calibration audio to a computing device. The computing device determines a calibration for the multiple playback devices in the venue based on the data representing the calibration audio recorded by the first mobile device and data representing calibration audio recorded by second mobile devices while the multiple playback devices played back the calibration audio.

An example method of operation may include initiating an automated tuning procedure, detecting via one or more microphones a sound measurement associated with an output of one or more speakers at two or more locations, determining a number of speech transmission index (STI) values equal to a number of microphones, and averaging the speech transmission index values to identify a single speech transmission index value.

A system includes a first device having a microphone associated with a voice user interface (VUI) and a first network interface, a first processor connected to the first network interface and controlling the first device, a second device having a speaker and a second network interface, and a second processor connected to the second network interface and controlling the second device. Upon connection of the second network interface to a network to which the first network interface is connected, the second processor causes the second device to output an identifiable sound through the speaker. Upon detecting the identifiable sound via the microphone, the first processor adds information identifying the second device to a data store of devices to be controlled when the first device activates the VUI.

Embodiments are provided for intelligently activating an amplifier in a playback device based on proximity detection. The playback device may be in a quasi-idle state when the playback device is not rendering media content. The quasi-idle state of the playback device may involve an amplifier in the playback device being inactive, while some other components or modules of the playback devices remain active. The playback device may include a proximity sensor configured to detect movement relative to the playback device. If movement is detected indicating that a user input to cause the playback device to render media content is anticipated, the amplifier may be pre-emptively activated such that the playback device enters an active state from the quasi-idle state. In some cases, the playback device may send a message to one or more other playback devices to cause the other playback devices to enter an active state.