DCT

2:26-cv-05476

Crestwood I A LLC v. Sonos Inc

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Amended Complaint
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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:26-cv-05476, C.D. Cal., 09/04/2026
  • Venue Allegations: Venue is based on Defendant Sonos, Inc. being headquartered and residing in the Central District of California, where it also allegedly conducts business and commits acts of infringement.
  • Core Dispute: Plaintiff alleges that Defendant's networked speaker products and associated software, including the "Trueplay" feature, infringe a portfolio of eight patents related to technologies for calibrating speaker audio output to a specific room environment.
  • Technical Context: The technology involves using a microphone, typically on a mobile device, to measure a room's acoustic response to test signals and then applying corrective filters to improve audio fidelity for subsequent playback.
  • Key Procedural History: The complaint alleges an extensive history of Defendant's knowledge of the technology, including citations to the patents' parent application during the prosecution of Defendant's own patents. It also references an Inter Partes Review (IPR) proceeding where the Patent Trial and Appeal Board (PTAB) reportedly found claims of a Sonos patent related to the accused "Trueplay" feature to be anticipated by the publication that led to Plaintiff's asserted patents. The complaint also notes that pre-suit notice of infringement was provided.

Case Timeline

Date Event
2012-02-21 Priority Date for all Asserted Patents
2015-10-07 Application for '996 Patent cited in office action for a Sonos patent application
2016-09-06 U.S. Patent No. 9,438,996 Issues
2016-12-06 A Sonos patent issues citing the application for the '996 Patent
2018-01-30 U.S. Patent No. 9,883,315 Issues
2019-03-26 U.S. Patent No. 10,244,340 Issues
2020-11-03 U.S. Patent No. 10,827,294 Issues
2021-01-08 Google answer in Sonos v. Google alleges Sonos patent is invalid based on '996 Patent's parent publication
2021-02-05 Google files IPR petition against a Sonos patent, using the '996 Patent's parent publication as prior art
2022-03-11 PTAB institutes IPR against Sonos patent based on '996 Patent's parent publication
2022-05-31 U.S. Patent No. 11,350,234 Issues
2023-02-15 PTAB issues Final Written Decision finding Sonos patent claims anticipated by '996 Patent's parent publication
2023-08-15 U.S. Patent No. 11,729,572 Issues
2024-12-31 U.S. Patent No. 12,185,078 Issues
2026-03-03 Plaintiff sends pre-suit notice of infringement to Defendant
2026-05-21 Plaintiff files original complaint
2026-09-04 Plaintiff files amended complaint

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 Invention Explained

  • Problem Addressed: The patent describes the problem of audio quality being "significantly degraded by physical factors such as room geometry, surface materials, speaker placement, and listener position" Compl. ¶ 20 '996 Patent, col. 1:24-35 It notes that prior calibration techniques were often "cumbersome, inconvenient, and expensive" and required specialized equipment and expertise, making them unsuitable for ordinary users in varied environments Compl. ¶ 21 '996 Patent, col. 2:35-46
  • The Patented Solution: The invention proposes using a portable device, such as a smartphone, to manage the calibration process Compl. ¶ 17 The process involves playing test signals through one or more speakers, capturing the resulting sound at multiple locations in the environment using the portable device's microphone, and then calculating corrective adjustments '996 Patent, abstract '996 Patent, col. 4:34-53 A key aspect of the solution is accounting for the unique distortion of the measurement microphone itself by using its "transfer function," which can be retrieved from a remote database, to isolate the room's acoustic effects Compl. ¶ 17 '996 Patent, col. 5:5-19
  • Technical Importance: This approach democratized high-fidelity audio calibration, enabling consumers to optimize sound systems in everyday, non-ideal listening environments using hardware they already possessed Compl. ¶ 22 '996 Patent, col. 2:38-45

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 6, 8, 9, and 10 Compl. ¶ 87
  • Independent Claim 1 of the '996 Patent recites the essential elements of a method for calibrating speakers:
    • Positioning a microphone of a portable device at a first location.
    • Initiating a "first playback" of a "first piece of audio content" over a first speaker and a "second playback" of a "second piece of audio content" over a second speaker, where the content is different and the playbacks overlap at least in part.
    • Detecting the first playback with the microphone.
    • Repositioning the microphone to another location.
    • Initiating and detecting a "third playback" of a "third piece of audio content" from the first speaker.
    • Determining adjustments for future audio playback based on the detected first and third playbacks.
    • The determination step includes accessing a system information file of the portable device to determine the microphone's transfer function and using that function in the calculation.
    • Applying the determined adjustments to subsequent audio content.

U.S. Patent No. 9,883,315 - "Systems and methods for calibrating speakers"

  • Issued: January 30, 2018

The Invention Explained

  • Problem Addressed: The '315 Patent shares a common specification with the '996 Patent and addresses the same problem of audio degradation in real-world environments Compl. ¶ 7
  • The Patented Solution: This patent claims a specific calibration method where the same "audio content" is played through a speaker and captured by a portable device's microphone at two different locations Compl. ¶ 30 '315 Patent, cl. 1 By holding the audio content constant, the system can isolate differences caused by the change in microphone position. The method also requires accounting for the microphone's transfer function, which is retrieved from the portable device itself, to ensure the measured differences reflect the environment rather than the recording device Compl. ¶ 30 '315 Patent, cl. 1
  • Technical Importance: This technique provides a method for calibrating audio output based on how sound propagates across a physical space, offering a more robust analysis than single-point measurements Compl. ¶ 30

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 4, 5, 8, 9, and 10 Compl. ¶ 94
  • Independent Claim 1 of the '315 Patent recites the essential elements of a method for calibrating speakers:
    • Positioning a microphone of a portable device at a first location.
    • Initiating and detecting a "first playback" of "a piece of audio content" over a speaker.
    • Repositioning the microphone to a second, different location.
    • Initiating and detecting a "second playback" of the same "piece of audio content" over the speaker.
    • Determining adjustments based on the detected first and second playbacks.
    • The determination step comprises accessing a system information file to determine the microphone's transfer function and using that function in the calculation.
    • Applying the determined adjustments to "additional audio content."

Multi-Patent Capsule Summaries

  • U.S. Patent No. 10,244,340

    • Title: "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS" (Issued March 26, 2019)
    • Technology Synopsis: The '340 Patent claims a calibration architecture that combines multi-location acoustic measurements with device-specific calibration data retrieved from a "remote system" Compl. ¶ 31 The process uses a "device identifier" to obtain the microphone's transfer function via a network, which is then used to determine and apply playback adjustments Compl. ¶ 31 '340 Patent, cl. 1
    • Asserted Claims: Independent claim 1 and dependent claims 4, 5, 8, and 9 Compl. ¶ 101
    • Accused Features: The "Trueplay" family of features Compl. ¶¶44-45

  • U.S. Patent No. 10,827,294

    • Title: "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS" (Issued November 3, 2020)
    • Technology Synopsis: The '294 Patent claims a calibration technique coordinated by a "portable electronic device" that establishes a network connection with a speaker system Compl. ¶ 33 The device directs the user to reposition it within the environment while initiating playback and capturing measurements at multiple locations, integrating user interface control with the measurement process Compl. ¶ 33 '294 Patent, cl. 11
    • Asserted Claims: Independent claim 11 and dependent claims 13, 14, 17, 18, and 20 Compl. ¶ 108
    • Accused Features: The "Trueplay" family of features Compl. ¶¶44-45

  • U.S. Patent No. 11,350,234

    • Title: "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS" (Issued May 31, 2022)
    • Technology Synopsis: The '234 Patent claims a method involving a single playback of audio content from an "Internet music library" over a network connection Compl. ¶ 34 A portable device captures a first portion of the playback at one location and a second portion at another location, using these samples to determine adjustments Compl. ¶ 34 '234 Patent, cl. 1
    • Asserted Claims: Independent claim 1 and dependent claims 3, 4, and 9 Compl. ¶ 115
    • Accused Features: The "Trueplay" family of features Compl. ¶¶44-45

  • U.S. Patent No. 11,729,572

    • Title: "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS" (Issued August 15, 2023)
    • Technology Synopsis: The '572 Patent claims a calibration technique initiated by "identifi[ed]...change[s] in an environment" and performed using a microphone on the "network-connected speaker system itself" rather than an external device Compl. ¶ 35 This enables automatic, environment-aware calibration that adapts to real-world changes Compl. ¶ 35 '572 Patent, cl. 1
    • Asserted Claims: Independent claim 1 and dependent claims 10 and 14 Compl. ¶ 122
    • Accused Features: The "Automatic Trueplay" and "TrueCinema" features (Compl. ¶¶51; 54; 55).

  • U.S. Patent No. 12,185,078

    • Title: "SYSTEMS AND METHODS FOR CALIBRATING SPEAKERS" (Issued December 31, 2024)
    • Technology Synopsis: The '078 Patent claims a technique where an electronic device directs successive playbacks of audio through a speaker system and captures the resulting sound at different locations Compl. ¶ 36 The method involves separate playback passes and location-specific captures to measure how a speaker's output changes across physical space, yielding calibration that reflects in-room acoustic behavior Compl. ¶ 36 '078 Patent, cl. 1
    • Asserted Claims: Independent claim 1 and dependent claims 3, 4, 5, 10, 11, and 13 Compl. ¶ 129
    • Accused Features: The "Trueplay" family of features Compl. ¶¶44-45

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are network-connected speaker and home-audio products sold by Sonos, including the Era, Five, One, Play, Move, Roam, Arc, and Beam product lines, among others Compl. ¶¶44; 50 The specific accused features are software-based calibration processes collectively referred to as "Trueplay," which includes "advanced tuning," "Automatic Trueplay," "quick tuning," and "TrueCinema" Compl. ¶ 45 Compl. ¶ 49 Compl. ¶ 51 Compl. ¶ 53 Compl. ¶ 55

Functionality and Market Context

  • The "Trueplay" feature, available through the Sonos App, directs a Sonos speaker to play test tones while the microphone of a portable device (e.g., an iPhone or iPad) records the audio at multiple positions in a room Compl. ¶ 46 The complaint includes a screenshot from the Sonos App instructing the user to "move your arm up and down as you move around the room" during the tuning process Compl. p. 16 Based on these measurements, the Sonos system determines and applies "environment-specific adjustments" to subsequent playback Compl. ¶ 46
  • Variations of this process are also accused. "Automatic Trueplay" is alleged to use microphones built into the speaker itself to "autonomously recalibrate playback without user intervention" Compl. ¶ 51 "Quick tuning" also uses the speaker's built-in microphone for a faster tuning process Compl. ¶ 53
  • The complaint alleges that Trueplay is a "central selling point" and "key differentiator" for Sonos's products, promoted as a way to improve audio performance in the listener's specific environment Compl. ¶ 45 Compl. ¶ 59 The complaint includes a screenshot of the Sonos App describing how "Trueplay optimizes the sound for your environment" Compl. p. 15

IV. Analysis of Infringement Allegations

The complaint alleges that the accused Trueplay processes meet every limitation of the asserted claims but does not provide claim charts in its body text, instead referencing exhibits not included in the provided document Compl. ¶ 87 Compl. ¶ 94 The following narrative summary outlines the core infringement theory presented in the complaint.

The central allegation is that the "Trueplay Calibration Process" practices the patented methods (Compl. ¶¶46; 87; 94). According to the complaint, a user running the Sonos App on a portable device is guided to perform the calibration Compl. ¶ 57 This involves the app directing Sonos speakers to play "test tones" (practicing the "initiating playback" steps) while the user moves the portable device around the room, allowing the device's microphone to capture the sound at "multiple positions" (practicing the "positioning" and "detecting" steps) Compl. ¶ 46 The complaint provides a screenshot of a "how-to video" in the Sonos app that provides explicit instructions for this process Compl. p. 20 The Sonos system then allegedly "determines environment-specific adjustments" (practicing the "determining adjustments" steps) and applies them to future music playback (practicing the "applying adjustments" steps) Compl. ¶ 46

Identified Points of Contention

  • Scope Questions: The various asserted patents have different requirements for the test audio. For example, claim 1 of the '996 Patent requires two different pieces of audio with overlapping playback, while claim 1 of the '315 Patent requires the same piece of audio to be played twice. The complaint alleges infringement of both but does not specify whether the "test tones" used by Trueplay are the same, different, or overlapping. This raises a technical question about whether a single accused process can simultaneously meet these mutually exclusive claim requirements.
  • Technical Questions: A core element of the asserted claims for the '996 and '315 patents is the use of a "microphone transfer function" determined by "accessing a system information file." The complaint does not provide direct evidence of how, or if, the Trueplay process accesses a device's system file to determine and use this specific function. The analysis may depend on whether discovery shows the limitation of Trueplay to certain devices (e.g., specific Apple products) is because Sonos is using device-specific acoustic data as claimed.

V. Key Claim Terms for Construction

The Term

"accessing a system information file of the portable device to determine a transfer function of the microphone" (from claim 1 of the '996 and '315 patents).

Context and Importance

This term is central to the invention's purported novelty and the infringement analysis. The definition of "determine" and the nature of the "access" will be critical. The case may turn on what actions by the accused system satisfy this multi-part limitation and what level of proof is required to show that a specific "transfer function" is being used, as opposed to a more generic correction. Practitioners may focus on this term because the complaint's infringement allegations depend heavily on it, yet the provided factual support is inferential.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: The shared specification suggests this can be a straightforward lookup process. It describes how an app can "reference the system information file of the smartphone to determine the model number of the phone, which can then be used to look up the transfer function in the database" (e.g.,'996 Patent, col. 5:11-16). This could support an interpretation where "determine" simply means to identify and retrieve a pre-calculated function associated with a device model, a potentially easier standard to meet.
  • Evidence for a Narrower Interpretation: A defendant might argue that "determine" requires a more active calculation or derivation of the transfer function, not merely a lookup based on a device's model number. The claim language requires accessing the file "to determine" the function, which could suggest that the file itself contains the necessary data for a determination, rather than just an identifier for an external lookup.

VI. Other Allegations

Indirect Infringement

The complaint alleges both induced and contributory infringement for all asserted patents (e.g., Compl. ¶¶89-90; Compl. ¶¶96-97). The inducement theory is based on allegations that Sonos directs and encourages customers to perform the infringing calibration methods through the Sonos App, including on-screen instructions and instructional videos Compl. ¶¶57-58 The contributory infringement theory is based on the allegation that the accused products are especially made for use in an infringing manner and are not staple articles of commerce with substantial non-infringing uses Compl. ¶ 90 Compl. ¶ 97

Willful Infringement

Willfulness is a central theme of the complaint, alleged for all asserted patents. The allegations are based on a long history of purported knowledge, including: (1) Defendant's patent prosecution history, where the application for the '996 Patent was allegedly cited against Defendant's own applications as early as 2015 Compl. ¶¶65-67; (2) prior litigation between Defendant and Google, where the '996 Patent's parent publication was asserted as invalidating prior art against Defendant's own patent on the Trueplay feature Compl. ¶¶70-72; (3) an IPR proceeding where the PTAB found claims of Defendant's patent were anticipated by that same publication Compl. ¶¶74-79; and (4) pre-suit written notice of infringement Compl. ¶ 82

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

  • A core issue will be one of technical proof: Can the Plaintiff demonstrate through discovery that the accused "Trueplay" process performs the specific, and in some cases mutually exclusive, steps recited in the various asserted claims? In particular, the case may turn on evidence showing whether and how Sonos accesses device-specific information to "determine a transfer function of the microphone," a critical limitation.
  • A second key question will be one of willfulness and damages: The complaint provides an extensive, detailed timeline alleging Defendant's long-standing knowledge of the patented technology, including through its own patent prosecution and prior litigation against a third party. A central battleground will likely be whether this history constitutes the "egregious" conduct necessary to support a finding of willful infringement and potential enhanced damages.
  • Finally, the litigation will raise a question of doctrinal consistency: How will Defendant contest infringement or validity in light of its own prior statements and litigation positions regarding the same underlying technology? The complaint's focus on the prior Sonos-Google litigation and the related IPR suggests that Defendant's arguments in those proceedings may be used to challenge its defenses in this case.