# US 2025/0097641 A1 · Systems and methods of distributing and playing back low-frequency audio content > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0097641 A1 - Document ID: US20250097641A1 - Status: Published application - Kind: A1 - Application number: 18/910,326 - Filed: 2024-10-09 - Published: 2025-03-20 - Earliest claimed: 2021-01-28 - Assignees: Sonos, Inc. - Applicants: Sonos, Inc. - Inventors: Paul MacLean; Chris Davies; Roberto Maria Dizon - Web page: https://patentgrep.com/patent/US20250097641A1 ## CPC - H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)} - H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone} - H04R 5/02: Spatial or constructional arrangements of loudspeakers - H04R 5/04: Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} - H04S 3/008: {in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02)} - H04S 7/308: {Electronic adaptation dependent on speaker or headphone connection} - H04R 2420/01: Input selection or mixing for amplifiers or loudspeakers - H04R 2420/07: Applications of wireless loudspeakers or wireless microphones - H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved - H04S 2400/07: Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) - H04S: STEREOPHONIC SYSTEMS ## Abstract Multichannel audio playback devices and associated systems and methods are disclosed herein. In some examples, a first playback device is configured to receive a source stream of audio content comprising left, right and center input channels. In a first mode, the first playback device is configured to play back audio via a plurality of transducers based on the left, right, and center input channels. In a second mode, in which the first playback device is bonded to second and third playback devices, the first playback device is configured to (i) play back audio via the plurality of transducers based on at least the center input channel, (ii) cause audio to be played via the second playback device based on at least the right input channel, and (iii) cause audio to be played via the third playback device based on at least the left input channel. ## Claims ### Claim 1 A first playback device, comprising: a plurality of transducers; a network interface; one or more processors; and data storage having instructions stored thereon that, when executed by the one or more processors, cause the first playback device to perform operations comprising: receiving, at the first playback device, a source stream of multichannel audio content comprising one or more first channels, a second channel, and a third channel; detecting locations of a second playback device and a third playback device relative to the first playback device; determining one or more acoustic characteristics of an environment in which the first playback device, the second playback device, and the third playback device are located; based on the detected locations and the determined acoustic characteristics, automatically configuring audio output parameters for the first playback device, the second playback device, and the third playback device; and causing synchronized playback of the multichannel audio content via the first playback device, the second playback device, and the third playback device according to the configured audio output parameters, wherein causing the synchronized playback comprises: playing back audio via the plurality of transducers based on at least a portion of the first channel(s); causing, via the network interface, audio to be played back via the second playback device based on at least the second channel and a first portion of the first channel(s); and causing, via the network interface, audio to be played back via the third playback device based on at least the third channel and a second portion of the first channel(s). ### Claim 2 (depends on 1) The first playback device of claim 1, wherein determining the one or more acoustic characteristics comprises: causing test audio content to be played back via at least one of the first playback device, the second playback device, or the third playback device; receiving, via one or more microphones, audio feedback from the played back test audio content; and analyzing the audio feedback to determine the acoustic characteristics. ### Claim 3 (depends on 1) The first playback device of claim 1, wherein detecting the locations comprises: receiving first location data from the second playback device indicating a first position relative to the first playback device; receiving second location data from the third playback device indicating a second position relative to the first playback device; and determining three-dimensional coordinates for the second playback device and the third playback device based on the received first and second location data. ### Claim 4 (depends on 1) The first playback device of claim 1, wherein the operations further comprise: detecting a change in location of at least one of the second playback device or the third playback device; automatically reconfiguring the audio output parameters based on the detected change in location; and adjusting the synchronized playback according to the reconfigured audio output parameters. ### Claim 5 (depends on 1) The first playback device of claim 1, wherein automatically configuring the audio output parameters comprises: determining that the detected location of the second playback device is unsuitable for playback of high-frequency audio content; and configuring the audio output parameters to route the high-frequency audio content to at least one of the first playback device or the third playback device. ### Claim 6 (depends on 1) The first playback device of claim 1, wherein the operations further comprise: determining playback capabilities of the second playback device and the third playback device; wherein automatically configuring the audio output parameters is further based on the determined playback capabilities. ### Claim 7 (depends on 6) The first playback device of claim 6, wherein determining the playback capabilities comprises: determining bass output capabilities of the second playback device and the third playback device; and wherein automatically configuring the audio output parameters comprises allocating low-frequency content among the first playback device, second playback device, and third playback device based on their respective bass output capabilities. ### Claim 8 A method comprising: receiving, at a first playback device, a source stream of multichannel audio content comprising one or more first channels, a second channel, and a third channel; detecting locations of a second playback device and a third playback device relative to the first playback device; determining one or more acoustic characteristics of an environment in which the first playback device, the second playback device, and the third playback device are located; based on the detected locations and the determined acoustic characteristics, automatically configuring audio output parameters for the first playback device, the second playback device, and the third playback device; and causing synchronized playback of the multichannel audio content via the first playback device, the second playback device, and the third playback device according to the configured audio output parameters, wherein causing the synchronized playback comprises: playing back audio via a plurality of transducers of the first playback device based on at least a portion of the first channel(s); causing, via a network interface of the first playback device, audio to be played back via the second playback device based on at least the second channel and a first portion of the first channel(s); and causing, via the network interface, audio to be played back via the third playback device based on at least the third channel and a second portion of the first channel(s). ### Claim 9 (depends on 8) The method of claim 8, wherein determining the one or more acoustic characteristics comprises: causing test audio content to be played back via at least one of the first playback device, the second playback device, or the third playback device; receiving, via one or more microphones, audio feedback from the played back test audio content; and analyzing the audio feedback to determine the acoustic characteristics. ### Claim 10 (depends on 8) The method of claim 8, wherein detecting the locations comprises: receiving first location data from the second playback device indicating a first position relative to the first playback device; receiving second location data from the third playback device indicating a second position relative to the first playback device; and determining three-dimensional coordinates for the second playback device and the third playback device based on the received first and second location data. ### Claim 11 (depends on 8) The method of claim 8, further comprising: detecting a change in location of at least one of the second playback device or the third playback device; automatically reconfiguring the audio output parameters based on the detected change in location; and adjusting the synchronized playback according to the reconfigured audio output parameters. ### Claim 12 (depends on 8) The method of claim 8, wherein automatically configuring the audio output parameters comprises: determining that the detected location of the second playback device is unsuitable for playback of high-frequency audio content; and configuring the audio output parameters to route the high-frequency audio content to at least one of the first playback device or the third playback device. ### Claim 13 (depends on 8) The method of claim 8, further comprising: determining playback capabilities of the second playback device and the third playback device; wherein automatically configuring the audio output parameters is further based on the determined playback capabilities. ### Claim 14 (depends on 13) The method of claim 13, wherein determining the playback capabilities comprises: determining bass output capabilities of the second playback device and the third playback device; and wherein automatically configuring the audio output parameters comprises allocating low-frequency content among the first playback device, second playback device, and third playback device based on their respective bass output capabilities. ### Claim 15 A tangible, non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a first playback device, cause the first playback device to perform operations comprising: receiving, at the first playback device, a source stream of multichannel audio content comprising one or more first channels, a second channel, and a third channel; detecting locations of a second playback device and a third playback device relative to the first playback device; determining one or more acoustic characteristics of an environment in which the first playback device, the second playback device, and the third playback device are located; based on the detected locations and the determined acoustic characteristics, automatically configuring audio output parameters for the first playback device, the second playback device, and the third playback device; and causing synchronized playback of the multichannel audio content via the first playback device, the second playback device, and the third playback device according to the configured audio output parameters, wherein causing the synchronized playback comprises: playing back audio via a plurality of transducers of the first playback device based on at least a portion of the first channel(s); causing, via a network interface of the first playback device, audio to be played back via the second playback device based on at least the second channel and a first portion of the first channel(s); and causing, via the network interface, audio to be played back via the third playback device based on at least the third channel and a second portion of the first channel(s). ### Claim 16 (depends on 15) The computer-readable medium of claim 15, wherein determining the one or more acoustic characteristics comprises: causing test audio content to be played back via at least one of the first playback device, the second playback device, or the third playback device; receiving, via one or more microphones, audio feedback from the played back test audio content; and analyzing the audio feedback to determine the acoustic characteristics. ### Claim 17 (depends on 15) The computer-readable medium of claim 15, wherein detecting the locations comprises: receiving first location data from the second playback device indicating a first position relative to the first playback device; receiving second location data from the third playback device indicating a second position relative to the first playback device; and determining three-dimensional coordinates for the second playback device and the third playback device based on the received first and second location data. ### Claim 18 (depends on 15) The computer-readable medium of claim 15, wherein the operations further comprise: detecting a change in location of at least one of the second playback device or the third playback device; automatically reconfiguring the audio output parameters based on the detected change in location; and adjusting the synchronized playback according to the reconfigured audio output parameters. ### Claim 19 (depends on 15) The computer-readable medium of claim 15, wherein automatically configuring the audio output parameters comprises: determining that the detected location of the second playback device is unsuitable for playback of high-frequency audio content; and configuring the audio output parameters to route the high-frequency audio content to at least one of the first playback device or the third playback device. ### Claim 20 (depends on 15) The computer-readable medium of claim 15, wherein the operations further comprise: determining playback capabilities of the second playback device and the third playback device; wherein automatically configuring the audio output parameters is further based on the determined playback capabilities, and wherein determining the playback capabilities comprises: determining bass output capabilities of the second playback device and the third playback device; and wherein automatically configuring the audio output parameters comprises allocating low-frequency content among the first playback device, second playback device, and third playback device based on their respective bass output capabilities.