Google LLC v. SoundClear Technologies LLC

1. Case Identification

• Case #: IPR2025-00345
• Patent #: 9,031,259
• Filed: February 10, 2025
• Petitioner(s): Google LLC
• Patent Owner(s): Soundclear Technologies, LLC
• Challenged Claims: 1-20

2. Patent Overview

• Title: Noise Reduction Apparatus, Audio Input Apparatus, Wireless Communication Apparatus, and Noise Reduction Method
• Brief Description: The ’259 patent discloses a noise reduction system that uses two microphones to capture sound. The system employs a speech segment determiner to identify voice components, a voice direction detector to determine the sound's origin, and an adaptive filter that uses this information to suppress unwanted noise from the audio signal.

3. Grounds for Unpatentability

Ground 1: Claims 1-3, 5, 6, 8, 13-15, and 17-19 are obvious over Kale

• Prior Art Relied Upon: Kale (Application # 2012/0027219)
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kale, which is analogous art in the field of audio signal processing, discloses every element of the independent claims. Kale’s “noise cancellation device” includes two microphones, computation/FFT modules that function as the claimed “speech segment determiner” by identifying speech signals from raw audio, a direction of arrival (DOA) module that serves as the “voice direction detector” by determining the speech source direction, and a “beamformer” that acts as the claimed “adaptive filter” to perform noise reduction using the speech and direction information.
  • Key Aspects: Petitioner contended that a person of ordinary skill in the art (POSITA) would have understood Kale’s use of cross-correlation in its DOA module to inherently perform a phase-difference calculation for direction finding, as recited in dependent claims 2 and 14. Similarly, Kale’s teaching of placing a null at the noise direction was argued to meet limitations in claims 3 and 15 regarding noise reduction based on which signal has a more advanced phase.

Ground 2: Claims 2, 3, 5, 6, 8, 9, 14, 15, and 17-20 are obvious over Kale in view of Namba

• Prior Art Relied Upon: Kale (Application # 2012/0027219), Namba (Application # 2010/0111329)
• Core Argument for this Ground:
  • Prior Art Mapping: This ground asserted that to the extent Kale does not explicitly disclose certain dependent claim features, Namba supplies the missing elements. Namba teaches a sound processing apparatus that explicitly uses both phase difference and volume/magnitude differences between microphone inputs to determine sound source direction. Namba’s distance/direction estimator was argued to teach the specific direction-finding techniques recited in claims 2, 5, 14, and 17 (based on phase and/or magnitude). Namba also discloses a "sound type estimation unit" that uses phase information to detect speech segments, teaching the limitations of claims 9 and 20.
  • Motivation to Combine: A POSITA would combine Namba with Kale to improve the accuracy of Kale’s voice direction detection, particularly in environments with sound reverberation or reflection. Namba explicitly teaches that combining phase and volume estimation methods enhances robustness, providing a clear reason to integrate its more sophisticated direction-finding techniques into Kale’s system.
  • Expectation of Success: Petitioner argued there was a high expectation of success because both references operate on similar principles of multi-microphone audio processing. Integrating Namba’s established mathematical formulas for phase and magnitude-based direction finding into Kale’s DOA module would have involved only routine skill and engineering.

Ground 3: Claims 1-3 and 12-15 are obvious over Li-730

• Prior Art Relied Upon: Li-730 (Application # 2011/0026730)

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner presented Li-730 as an alternative primary reference that discloses a complete audio processing apparatus for noise suppression. Li-730’s “voice active detector” (VAD) was mapped to the claimed “speech segment determiner,” as it determines speech presence by comparing a power ratio of microphone signals to a threshold. Li-730’s “beamformer” was mapped to the “voice direction detector,” as it receives the VAD output (speech segment information) and generates a steering vector to determine voice direction. Finally, Li-730’s “noise suppression unit” was mapped to the “adaptive filter,” as it suppresses noise using the microphone signals, the VAD output, and the directional information from the beamformer.
  • Key Aspects: This ground argued that Li-730 teaches reducing noise from the signal with the advanced phase (from the microphone closer to the speaker) using the signal with the delayed phase (from the farther microphone), directly anticipating the logic of claims 3 and 15. The arguments for independent apparatus claim 12, which adds limitations about the physical placement of microphones on a device, were also asserted to be met by Li-730's disclosure of a cell phone with microphones on its front and back panels.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 2-4, 7, and 14-16 are obvious over Kale and Li-638 (Application # 2012/0197638) to add a feature of stopping noise reduction when only speech is detected. Further, claims 10 and 11 were challenged as obvious over Kale and Yamada (Application # 2012/0128187) for using different sampling frequencies for the direction detector and the adaptive filter to improve accuracy and efficiency.

4. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §314(a) and §325(d). Regarding the Fintiv factors, Petitioner asserted that the parallel district court litigation is in its infancy with no trial date set, and the parties have made minimal investment in the proceeding. Regarding §325(d), Petitioner argued that none of the cited prior art references were previously presented to or evaluated by the patent examiner during prosecution, and that the asserted grounds show the examiner erred in allowing the claims.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-20 of the ’259 patent as unpatentable.