DCT

2:26-cv-05476

Crestwood I A LLC v. Sonos Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:26-cv-05476, C.D. Cal., 05/21/2026
  • Venue Allegations: Venue is alleged to be proper in the Central District of California because Defendant Sonos, Inc. is headquartered in the district, resides there, maintains a regular and established place of business, and has committed the alleged acts of infringement within the district.
  • Core Dispute: Plaintiff alleges that Defendant's audio products featuring "Trueplay" and related room-calibration technologies infringe a family of seven U.S. patents concerning systems and methods for calibrating speakers using a portable device.
  • Technical Context: The technology involves automatic acoustic equalization, where a system uses a microphone to measure a room's acoustic properties and adjusts speaker output to improve audio fidelity for that specific environment.
  • Key Procedural History: The complaint alleges an extensive history of Defendant's awareness of the asserted patent family, which shares a common 2012 priority date. This history includes Defendant's own patent prosecution activities where the parent application to the asserted patents was cited as prior art against Defendant as early as 2015. The complaint also details Defendant's prior litigation against Google, in which an Inter Partes Review (IPR) was instituted and found claims of a Sonos patent anticipated by the disclosure of the asserted patent family. Plaintiff also alleges it provided direct pre-suit notice of infringement to Defendant in March 2026.

Case Timeline

Date Event
2012-02-21 Patent Priority Date for all Asserted Patents
2015-10-07 Alleged date of Sonos's knowledge of the patent family's parent application ('071 publication) via a USPTO office action
2016-09-06 U.S. Patent No. 9,438,996 Issued
2016-12-06 A Sonos patent allegedly issues citing the '071 publication
2018-01-30 U.S. Patent No. 9,883,315 Issued
2019-03-26 U.S. Patent No. 10,244,340 Issued
2020-09-29 Sonos files suit against Google, allegedly putting its Trueplay technology at issue
2020-11-03 U.S. Patent No. 10,827,294 Issued
2021-01-08 Google alleges a Sonos patent is invalid over the '071 publication in litigation
2021-02-05 Google files an IPR petition against a Sonos patent, based on the '071 publication
2022-03-11 PTAB institutes the IPR against Sonos's patent
2022-05-31 U.S. Patent No. 11,350,234 Issued
2023-02-15 PTAB issues Final Written Decision finding Sonos patent claims anticipated by the '071 publication
2023-08-15 U.S. Patent No. 11,729,572 Issued
2024-12-31 U.S. Patent No. 12,185,078 Issued
2026-03-03 Plaintiff alleges sending pre-suit notice of infringement to Sonos
2026-03-12 Sonos allegedly acknowledges receipt of pre-suit notice
2026-05-21 Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,438,996 - "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS"

  • Issued: September 6, 2016 (the "'996 Patent")

The Invention Explained

  • Problem Addressed: The patent addresses the degradation of audio quality caused by environmental factors like room geometry, furnishings, and speaker placement Compl. ¶20 '996 Patent, col. 1:26-35 It notes that prior calibration methods were often "cumbersome, inconvenient, and expensive," making them impractical for ordinary consumers in varied listening environments Compl. ¶21 '996 Patent, col. 2:41-46
  • The Patented Solution: The invention proposes using a portable device, such as a smartphone, to simplify and automate speaker calibration Compl. ¶17 '996 Patent, abstract The system initiates playback of test signals from speakers, detects the signals using the portable device's microphone at multiple positions, and then calculates corrective equalization adjustments Compl. ¶¶17-18 A key aspect is the use of the microphone's known "transfer function"-retrieved from a database using the device's model information-to compensate for the microphone's own acoustic inaccuracies, thereby improving the calibration's precision Compl. ¶24 '996 Patent, col. 5:5-18 The specification explicitly contemplates application to "network connected speakers (e.g., such as those made and distributed by Sonos)" ('996 Patent, col. 2:53-56).
  • Technical Importance: This approach made sophisticated, environment-specific acoustic calibration accessible to the mass market by leveraging the capabilities of consumer electronic devices (Compl. ¶27).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 Compl. ¶81
  • Essential elements of independent claim 1 include:
    • Positioning a microphone of a portable device.
    • Initiating a first playback of a first piece of audio over a first speaker.
    • Initiating a second, different playback of a second piece of audio over a second speaker, where the first and second playbacks overlap.
    • Detecting the first playback with the microphone.
    • Repositioning the microphone to another location.
    • Initiating and detecting a third playback.
    • Determining adjustments based on the detected playbacks, which includes accessing a system information file to determine a transfer function of the microphone and using that function.
    • Applying the determined adjustments to subsequent audio content.
  • The complaint does not explicitly reserve the right to assert dependent claims, but this is standard practice.

U.S. Patent No. 9,883,315 - "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS"

  • Issued: January 30, 2018 (the "'315 Patent")

The Invention Explained

  • Problem Addressed: As a continuation of the '996 Patent, the '315 Patent addresses the same problem of audio degradation in non-ideal listening environments Compl. ¶20 Compl. ¶21
  • The Patented Solution: The '315 Patent, sharing a common specification with the '996 Patent, also describes a calibration method using a portable device ('315 Patent, abstract). The claims focus on a process that captures an "audio source" at multiple distinct physical locations to model location-dependent acoustic effects, such as how sound propagates across a space, rather than relying on a single-point measurement (Compl. ¶30; '315 Patent, col. 9:30-10:14).
  • Technical Importance: This technique improves calibration accuracy by accounting for spatial variations in the acoustic response of a room (Compl. ¶30).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 Compl. ¶88
  • Essential elements of independent claim 1 include:
    • Providing instructions for positioning a microphone at a first location.
    • Initiating and detecting a first playback over a speaker.
    • Providing instructions for repositioning the microphone at a second, different location.
    • Initiating and detecting a second playback.
    • Determining adjustments based on both detected playbacks and a microphone transfer function retrieved from a remote system via a web service.
    • Applying the adjustments to subsequent audio.
  • The complaint does not explicitly reserve the right to assert dependent claims.

Multi-Patent Capsules

  • Patent Identification: U.S. Patent No. 10,244,340, "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS," issued March 26, 2019 ('340 Patent).

  • Technology Synopsis: The '340 Patent claims a calibration architecture that combines multi-location measurements with retrieving the microphone's transfer function from a "remote system" using a "device identifier" sent via a network (Compl. ¶31). This retrieved data is then used to compute and apply adjustments (Compl. ¶31).

  • Asserted Claims: At least independent claim 1 is asserted Compl. ¶95

  • Accused Features: The "Trueplay Calibration Process" is accused of infringement Compl. ¶95

  • Patent Identification: U.S. Patent No. 10,827,294, "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS," issued November 3, 2020 ('294 Patent).

  • Technology Synopsis: The '294 Patent is directed to a calibration technique implemented through a "portable electronic device" that establishes a network connection with a speaker system, directs the user to reposition the device, initiates playback, and captures measurements at multiple locations (Compl. ¶33). It integrates user interface controls with network-based playback and measurement into a unified workflow (Compl. ¶33).

  • Asserted Claims: At least independent claim 11 is asserted Compl. ¶102

  • Accused Features: The "Trueplay Calibration Process" is accused of infringement Compl. ¶102

  • Patent Identification: U.S. Patent No. 11,350,234, "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS," issued May 31, 2022 ('234 Patent).

  • Technology Synopsis: The '234 Patent claims a technique where a portable device initiates playback of audio content from an "Internet music library" and captures measurements of that content at multiple locations to determine calibration adjustments (Compl. ¶34; Compl. ¶109).

  • Asserted Claims: At least independent claim 1 is asserted Compl. ¶109

  • Accused Features: The "Trueplay Calibration Process" is accused of infringement Compl. ¶109

  • Patent Identification: U.S. Patent No. 11,729,572, "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS," issued August 15, 2023 ('572 Patent).

  • Technology Synopsis: The '572 Patent claims a calibration technique that is triggered automatically by an "identifi[ed]...change[s] in an environment" (Compl. ¶35). It is performed using a microphone integrated into the "network-connected speaker system" itself, rather than an external device, enabling continuous, environment-aware adaptation of the audio output (Compl. ¶35).

  • Asserted Claims: At least independent claim 1 is asserted Compl. ¶116

  • Accused Features: The "Automatic Trueplay Accused Products and TrueCinema Accused Products" are accused of infringement Compl. ¶116

  • Patent Identification: U.S. Patent No. 12,185,078, "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS," issued December 31, 2024 ('078 Patent).

  • Technology Synopsis: The '078 Patent claims a technique involving successive, distinct playback signals through a speaker system, with the resulting audio captured at different locations (Compl. ¶36). Playback adjustments are determined based on the measured differences between the location-specific captures (Compl. ¶36).

  • Asserted Claims: At least independent claim 1 is asserted Compl. ¶123

  • Accused Features: The "Trueplay Calibration Process" is accused of infringement Compl. ¶123

III. The Accused Instrumentality

Product Identification

  • The accused instrumentalities are Sonos audio products capable of using the "Trueplay," "advanced tuning," "Automatic Trueplay," "quick tuning," and "TrueCinema" features (collectively, the "Calibration Processes") (Compl. ¶¶39-41; Compl. ¶51 n.2). The complaint lists a wide range of products including the Era, Five, One, Arc, and Move lines (Compl. ¶¶45, 49).

Functionality and Market Context

  • The "Trueplay Calibration Process" is a software feature, operated through the Sonos App on a portable device like an iPhone, that guides a user through a room calibration routine (Compl. ¶41). Screenshots in the complaint show the app instructing a user to move their device around the room while it records test tones from the speakers (Compl. ¶41; Compl. p. 12). Another visual shows a more advanced process for home theaters that first tunes for a primary seating position and then for the whole room Compl. p. 13
  • "Automatic Trueplay," available on portable products like the Move and Roam, uses the speaker's own built-in microphone to detect environmental changes and autonomously recalibrate audio without user intervention (Compl. ¶46). A screenshot shows the user interface for enabling this feature on a Roam 2 speaker Compl. p. 14
  • "TrueCinema" is a related feature that uses microphones embedded in Sonos Ace headphones to tune audio from a soundbar for a specific environment (Compl. ¶50). Visuals depict the user being instructed to face their TV for several seconds to complete the tuning Compl. p. 15
  • The complaint alleges that Sonos markets these calibration features as a key differentiator that provides superior sound quality, and describes them as "key benefits" in annual reports to investors (Compl. ¶¶40, 54-55).

IV. Analysis of Infringement Allegations

The complaint references exemplary claim charts attached as exhibits, which are not provided in the submitted documents Compl. ¶81 Compl. ¶88 The following tables are constructed based on the narrative allegations in the complaint and the language of the asserted patents.

'996 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
positioning a microphone of a portable device at a location in an environment; The user is instructed via the Sonos App to position their portable device (e.g., an iPhone) within the room to be calibrated. ¶41 col. 4:44-50
initiating first playback by an audio source of a first piece of audio content over a first speaker; The Sonos system plays a test tone through a first speaker in the environment. ¶41 col. 4:50-51
initiating second playback...of a second piece of audio content over a second speaker, wherein the first piece of audio content is different from the second piece of audio content, and in which first playback...overlaps, at least in part, with second playback... The complaint alleges infringement by systems including stereo pairs and surround sound setups, which would involve playback from multiple speakers. The complaint alleges these systems meet every limitation of the claim. ¶43; ¶81 col. 6:53-65
determining, based at least in part on the detected first playback...one or more adjustments...wherein determining...includes: accessing a system information file of the portable device to determine a transfer function of the microphone... The Sonos system is alleged to automatically compute room-specific adjustments. The complaint alleges the system accounts for the microphone's transfer function by using the device's system information file. ¶17; ¶24 col. 5:5-18
applying the one or more adjustments to the additional audio content before it is played by the first speaker. The Sonos system applies the determined adjustments as equalization (EQ) settings for subsequent audio playback. ¶41; ¶25 col. 5:20-32

'315 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
providing instructions for positioning the microphone of the portable device at a first location... The Sonos App provides explicit instructions and visuals guiding the user on where and how to move the portable device during the calibration process. ¶41; ¶52 col. 4:44-50
initiating first playback by an audio source of a first piece of audio content over a speaker; The Sonos system plays a series of test tones through one or more speakers. ¶41 col. 4:50-51
detecting the first playback...by the microphone at the first location; The microphone on the user's portable device records the audio from the test tones at various positions as the user moves around the room. ¶41 col. 4:38-44
providing instructions for positioning a microphone at a second location...different from the first location; The Sonos App instructs the user to "move your arm up and down as you move around the room," which involves capturing audio at multiple distinct locations. ¶41 col. 4:50-52
determining...one or more adjustments...wherein determining...comprises: retrieving the transfer function of the microphone from a set of microphone transfer functions using a web service. The complaint alleges the system computes adjustments by accessing device-specific data for the microphone from a database, which may be Internet-accessible. ¶24 col. 5:5-19
applying the one or more adjustments to the additional audio content before it is played... The resulting adjustments are applied to the Sonos speakers to "optimize the sound for your environment." ¶41 col. 5:20-32

Identified Points of Contention

  • Scope Questions: Claim 1 of the '996 Patent requires overlapping playback from two different pieces of audio over two different speakers. The complaint broadly accuses the Trueplay process, which is also available for single speakers (Compl. ¶42). An issue for the court may be whether the standard Trueplay process, when used with a single speaker, meets the limitations of this specific claim, or if infringement is limited to multi-speaker setups like stereo pairs or home theaters.
  • Technical Questions: A central technical question will be the nature of the microphone compensation used by Sonos. The patents claim a specific method of accessing a "system information file" to determine a device-specific "transfer function" to correct for the microphone's unique distortions Compl. ¶24 The case may turn on what evidence shows Sonos's system performs this specific function, as opposed to applying a more generic or averaged correction factor not tied to the specific portable device model.

V. Key Claim Terms for Construction

  • The Term: "system information file" (from '996 Patent, cl. 1; '315 Patent, cl. 1)

    • Context and Importance: This term is critical for infringement, as the patents require its use to determine the microphone's transfer function. Practitioners may focus on this term because its definition will determine whether Sonos's method of identifying the portable device (e.g., by its model name) and retrieving corresponding data meets this limitation.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification suggests this can be accomplished by retrieving a "model identifier" from the device and using it to look up data, which may support an interpretation that any file or data structure providing such an identifier qualifies Compl. ¶24 '996 Patent, col. 5:14-18
      • Evidence for a Narrower Interpretation: The use of the specific phrase "system information file" may suggest an official, operating-system-level file with a defined structure, rather than any general application-level data. The defense may argue for a narrower construction to distinguish Sonos's implementation.

  • The Term: "transfer function of the microphone" (from '996 Patent, cl. 1; '315 Patent, cl. 1)

    • Context and Importance: This term defines the data used to correct for the microphone's inaccuracies, a core part of the claimed invention. The dispute will likely center on whether the correction data used by Sonos is sufficiently detailed and specific to qualify as a "transfer function."
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent describes using a "response curve" to "subtract[] out" the microphone's characteristics, which could support a broader meaning that includes any data representing the microphone's frequency response '996 Patent, col. 5:8-18
      • Evidence for a Narrower Interpretation: The term "transfer function" has a specific meaning in signal processing as a mathematical representation of a system's input-output relation. A party could argue the claims require a complete, formal mathematical function, not just a set of correction values or a simplified curve, potentially narrowing the claim scope.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that Sonos induces infringement by providing the Sonos App, which contains the software and on-screen instructions that "directing and controlling its customers' performance" of the patented calibration methods (Compl. ¶¶52-53; Compl. ¶82; Compl. ¶89). It is alleged that Sonos conditions the benefits of Trueplay on users performing these steps (Compl. ¶53). The complaint also alleges contributory infringement, arguing the accused products are especially adapted for infringing use and are not staple articles of commerce (Compl. ¶84; Compl. ¶91).
  • Willful Infringement: The complaint asserts willfulness based on a detailed timeline of alleged knowledge. The allegations include: (1) Sonos's specific mention in the patents' common specification (Compl. ¶58); (2) Sonos's alleged awareness of the patent family's parent application ('071 publication) from its own patent prosecution dating back to 2015 (Compl. ¶60); (3) knowledge gained during Sonos's litigation against Google, where the '071 publication was successfully used in an IPR to invalidate a Sonos patent on similar technology (Compl. ¶¶65-74); and (4) direct written notice of infringement sent in March 2026 (Compl. ¶77).

VII. Analyst's Conclusion: Key Questions for the Case

  • A primary issue will be one of technical proof: Can Plaintiff produce evidence showing that Sonos's Trueplay system performs the specific steps of accessing a "system information file" to retrieve a device-specific "transfer function of the microphone" to correct for acoustic distortions, as required by the claims, or does Sonos employ a different, non-infringing method of compensation?
  • A second issue will be one of claim scope: Several patents in the family recite highly specific method steps (e.g., overlapping playback from different speakers in the '996 Patent; triggering based on environmental change in the '572 Patent). A key question is whether the various accused features ("Trueplay," "Automatic Trueplay," etc.) map onto these specific limitations, or if the asserted claims are narrower than the full range of accused functionality.
  • A third, and potentially dispositive, issue for damages will be willfulness: The complaint constructs a strong narrative of Sonos's long-standing knowledge and willful blindness based on its own patent prosecution and prior litigation history. The case may turn on whether Sonos can provide a sufficient non-infringement or invalidity defense to rebut the allegation that it deliberately disregarded a known and obvious risk of infringement.
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