Sonos Inc v. Vocalife LLC

1. Case Identification

• Case #: IPR2022-00469
• Patent #: RE47,049
• Filed: January 19, 2022
• Petitioner(s): Sonos, Inc
• Patent Owner(s): Vocalife, LLC
• Challenged Claims: 1-35

2. Patent Overview

• Title: Method and System for Enhancing a Target Sound Signal
• Brief Description: The ’049 patent discloses a system for enhancing a target sound signal (e.g., speech) in a noisy environment. The system uses a microphone array to capture sounds, which are then processed by a digital signal processor (DSP) comprising three main functional units: a sound source localization unit, an adaptive beamforming unit, and a noise reduction unit.

3. Grounds for Unpatentability

Ground 1: Obviousness over Sato and Gareta

• Claims: 1-4, 6-12, 14-15, and 17-35 are obvious over Sato in view of Gareta.
• Prior Art Relied Upon: Sato (a 2009 IEEE conference paper) and Gareta (a 2007 doctoral thesis).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sato disclosed the core architecture of the ’049 patent: a "speech dialogue module" using a single DSP with distinct functional "cores" for Direction-of-Arrival (DOA) estimation (the claimed sound source localization unit), adaptive beamforming for a microphone array (the claimed adaptive beamforming unit), and adaptive noise cancellation (the claimed noise reduction unit). However, Petitioner contended Sato described these functions at a high level. Gareta was asserted to provide the missing technical details, describing the "fundamentals of array signal processing," including the specific algorithms and mathematical equations for implementing these functions. For example, Gareta taught using SRP-PHAT for sound localization and the Generalized Sidelobe Canceller (GSC) architecture for adaptive beamforming, both well-known techniques.
  • Motivation to Combine: Petitioner asserted a person of ordinary skill in the art (POSITA) implementing Sato's high-level system would have been motivated to consult a fundamental text like Gareta for the well-known, underlying algorithmic details needed to make the system work. Both references were in the same field of microphone array signal processing and addressed the identical problem of improving sound quality in noisy environments. The combination was presented as the application of known techniques to a known system to achieve predictable results.
  • Expectation of Success: A POSITA would have had a high expectation of success because Gareta described established, commonly used algorithms and provided experimental results demonstrating their success.

Ground 2: Obviousness over Sato, Gareta, and Liu

• Claims: 5 and 13 are obvious over Sato and Gareta in view of Liu.
• Prior Art Relied Upon: Sato, Gareta, and Liu (a 2001 IEEE workshop paper).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the Sato and Gareta combination to address claims 5 and 13, which added limitations related to sub-band adaptive filtering. These claims required the adaptive filtering to be performed in sub-bands using an analysis filter bank, an adaptive filter matrix, and a synthesis filter bank. Petitioner argued that Liu disclosed exactly this—a "subband adaptive GSC" architecture that splits signals from a fixed beamformer and blocking matrix into frequency sub-bands using an analysis filter bank, processes each sub-band with an independent multichannel adaptive filter (the claimed "adaptive filter matrix"), and recombines them with a synthesis filter bank.
  • Motivation to Combine: A POSITA would combine Liu with the system of Sato and Gareta to improve performance. The references explained that processing broadband acoustic signals in frequency sub-bands was a known technique to improve convergence speed and lower computational complexity. Liu provided a successful, concrete architecture for applying this known technique to the GSC beamformer taught by Gareta.
  • Expectation of Success: The technique was well-known, and Liu's disclosure of a specific, successful implementation for a GSC architecture would have given a POSITA confidence that it could be integrated into the Sato/Gareta system.

Ground 3: Obviousness over Sato, Gareta, and Baumhauer

• Claims: Claim 16 is obvious over Sato and Gareta in view of Baumhauer.

• Prior Art Relied Upon: Sato, Gareta, and Baumhauer (Patent 5,506,908).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground addressed claim 16, which added a limitation requiring one or more audio codecs for converting analog sound signals to digital and reconverting the processed digital signals back to analog. Petitioner argued that the systems of Sato and Gareta operated in the digital domain. Baumhauer was cited for its disclosure of a directional microphone system that explicitly used codecs to convert analog signals from microphones into digital signals for processing by a DSP, and another codec to convert the digital output back to an analog form for transmission.
  • Motivation to Combine: Petitioner asserted that a POSITA would have understood that implementing a digital signal processing system like Sato's, which receives real-world analog sounds from microphones, would necessarily require analog-to-digital conversion. Baumhauer taught a conventional way to implement this necessary component. The combination was argued to be nothing more than adding a fundamental, well-understood element (codecs) to the Sato/Gareta system to enable its basic operation.
  • Expectation of Success: By the priority date of the ’049 patent, the use of codecs for analog/digital conversion in DSP systems was fundamental and widespread, leading to a high expectation of success.

• Additional Grounds: Petitioner asserted alternative grounds (1B, 2B, 3B) adding the reference Li (a 2009 conference paper) to the combinations above. These grounds argued that to the extent Gareta did not sufficiently disclose representing signal delay "in terms of number of samples," Li explicitly taught this by providing a delay equation that multiplied a time-based delay by the sampling frequency to yield the delay in samples.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under Fintiv was improper because the parallel district court litigation was in its early stages. Petitioner had filed a motion to stay the litigation pending the outcome of the inter partes review (IPR), and noted that the court had granted stays in related litigations. Petitioner also stipulated that if the IPR was instituted, it would not pursue the same invalidity grounds in the district court litigation, thereby mitigating concerns of duplicative efforts and conserving judicial resources. Petitioner further argued that denial under General Plastic or §325 would be improper because the petition raised new prior art and grounds not previously considered by the USPTO.

5. Relief Requested

• Petitioner requests institution of an IPR and cancellation of claims 1-35 of the ’049 patent as unpatentable.