Federal Circuit Reverses PTAB Findings of Unpatentability for Google’s ‘Hotword’ Patents

The U.S. Court of Appeals for the Federal Circuit (CAFC) on Tuesday reversed and remanded two Patent Trial and Appeal Board decisions that had found Google’s patents for improvements to “hotword” detection unpatentable. The opinion was authored by CAFC Chief Judge Moore.

“Hotwords” are phrases like “Hey Siri” and “OK Computer” that are used to activate voice assistants. Google’s U.S. patents 10,134,398 and 10,593,330 are directed to improvements that “address the problem of triggering multiple devices with a single hotword” by suppressing the reaction in other devices while the intended device reacts.

Sonos, Inc. filed a petition for inter partes review (IPR) with the PTAB challenging certain claims of both patents and the Board ultimately held certain claims of each patent either unpatentable as anticipated by the prior art or obvious over it.

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

The court found that the Board read column 8 of Rosenberger incorrectly and its conclusion that column 8 “discloses a device exchanging weighted signals (i.e., the claimed messages) while in a low power ‘listening’ mode to determine whether to exit the low power mode to interact with a user” was unsupported by substantial evidence.

The Board relied on Sonos’ expert testimony to support its conclusion, but the Federal Circuit said that column 8 “describes embodiments where upon detecting a spoken trigger or command phrase, the devices exit the low power ‘listening’ mode to calculate and exchange weighted signals.” This means it cannot anticipate the claims because “it fails to disclose the limitations directed to exchanging messages while in a low power mode.”

While Sonos argued that Rosenberger’s column 8 could be read to disclose a device that “changes its status light,” which “corresponds to a change from the low power ‘listening’ mode to a mode that consumes more power to handle a user’s speech commands,’” Moore’s opinion said there was no evidence to support that. Likewise, Sonos’ argument that it was reasonable for the Board to determine that Rosenberger’s “disclosure that the device ‘wakes up’ indicates the device exits the low power ‘listening’ mode after ‘determining that it is in a better position to handle subsequent user interaction than any other device’” was not supported by substantial evidence. And Sonos’ alternative theory that the CAFC could affirm based on Rosenberger’s disclosure that the devices remain in a low power mode in which they would consume less power than they would in operating mode also failed. Sonos claimed “this reduced power consumption during coordination meets the parties’ agreed-upon construction for ‘low power mode’ of ‘an operating mode or state in which power is conserved’” but the Federal Circuit said the Board made no fact-findings regarding this theory and therefore it must consider the issue on remand.

The CAFC thus reversed the PTAB’s decisions and remanded for further proceedings.

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Author: almoond