The U.S. Court of Appeals for the Federal Circuit (CAFC) issued a decision on June 9 in Google LLC v. Sonos, Inc., reversing Patent Trial and Appeal Board (PTAB) final written decisions (FWDs) that held claims of two Google patents unpatentable. The court found the Board’s anticipation findings were not supported by substantial evidence and remanded the case for further proceedings.

Google LLC owns U.S. Patent Nos. 10,134,398 and 10,593,330, which are directed to improvements in “hotword” detection in sound-enabled devices that address the problem of triggering multiple devices with a single hotword, such as “Hey Siri” or “OK computer.” The claimed improvements cause an intended device to respond to a hotword while suppressing responses on other devices. Devices detect and process a speech command, compute a confidence score indicating whether the command is a hotword, and transmit that score to other devices. A device then determines whether to remain in a sleep state or transition to an active state based on the exchange of confidence scores with other devices.

Sonos, Inc. filed petitions for inter partes review (IPR) challenging claims of both patents as anticipated by and obvious over prior art. The Board held certain claims unpatentable as anticipated by U.S. Patent No. 8,340,795 and held additional claims unpatentable as obvious over Rosenberger in view of U.S. Patent Application Publication No. 2014/0163978. 

On appeal, Google argued the Board reversibly erred in holding the independent claims of the ‘398 and ‘330 patents unpatentable as anticipated by Rosenberger. Specifically, Google argued the Board’s finding that Rosenberger discloses transmitting messages while the computing device remains in a low power mode was unsupported by substantial evidence, and the CAFC agreed.

The Board had relied on column 8 of Rosenberger to support its finding that the reference discloses a device exchanging weighted signals while in a low power “listening” mode to determine whether to exit that mode to interact with a user. The CAFC held that column 8 of Rosenberger “never discloses exchanging weighted signals, let alone exchanging weighted signals while the device remains in the low power ‘listening’ mode.”

The Board credited the testimony of Sonos’ expert, Dr. Johnson, who opined that while Rosenberger generally discloses devices configured to exit a low power mode before exchanging weighted signals, the column 8 passage discloses an instance where devices remain in the low power “listening” mode while exchanging weighted signals according to a coordination method. The CAFC found, however, that the “device coordination discussion” column 8 references and on which Dr. Johnson describes embodiments where devices exit the low power “listening” mode to calculate and exchange weighted signals upon detecting a spoken trigger or command phrase.

Sonos argued the Board reasonably found that column 8’s disclosure of a device that “changes its status light” corresponded to a transition out of the low power “listening” mode into a higher power mode. The CAFC rejected that reading, finding Rosenberger does not disclose that a change in status light indicates any such transition. Column 8 instead discloses that “the device beeps, changes its status light 34 or plays a prerecorded or synthesized audio message…to prompt the user to say one of the speech commands,” with Rosenberger never suggesting the status light change signals a shift to higher power consumption.

Moreover, Sonos argued the Board reasonably found that column 8’s reference to a device “waking up” indicated the device exited the low power “listening” mode after determining it was in a better position to handle subsequent user interaction than other devices. The CAFC found that reading was unsupported. Column 8 discloses “determining that [a device] is in a better position to handle subsequent user interaction” and “instruct[ing] [the device] to wake up” as alternatives separated by “or,” not as causally connected steps. The Board found that a device deemed in a “better position” than others would exit low power mode and “wake up” to respond to a subsequent user query. That conclusion was not supported by substantial evidence because it assumed a causal link between two steps that Rosenberger describes as independent alternatives.

Sonos also argued on appeal that the CAFC could affirm an alternative theory that Rosenberger’s devices stay in a low power state distinct from the self-described “listening” mode during coordination, since components handling user interaction and speech processing consume less power at that time. Sonos contended that this reduced power consumption satisfies the agreed-upon claim construction for “low power mode” as “an operating mode or state in which power is conserved.” The CAFC declined to address the theory, noting that the Board made no factual findings on it in either FWD. The court cited Regents of the University of California v. Broad Institute, Inc., and explained, “it is not our role to ask whether substantial evidence supports fact-findings not made by the Board, but instead whether such evidence supports the findings that were in fact made,” and left the issue for the Board on remand.

The CAFC reversed the Board’s holdings that the challenged claims of the ‘398 and ‘330 patents were unpatentable as anticipated by Rosenberger or obvious over Rosenberger and Basye, and remanded for further proceedings consistent with the opinion. The costs were awarded to Google.