The tech giant maintained the option has always been opt-in, but the company has now clarified that real people are involved in transcribing clips obtained through its virtual assistant.
Google's move is seen as a positive by digital rights campaigners, and Jim Killock - Open Rights Group executive director - said: "Companies should do the right thing and make sure people choose to be recorded.
"They shouldn't be forced into checking that every company isn't intruding into their homes and daily conversations."
Google has revealed around one in 500 of all user audio clips will be subject to human checks.
The company's promise comes after Apple moved to its own opt-in model in August, while Amazon and Facebook still make users ask to be excluded from the recordings.
Google Assistant manager Nina Tasca says those who had previously agreed to let their audio be used would have to do so again, with the settings menu making it clear that humans are involved.
Meanwhile, users will soon be able to set the sensitivity of their devices to activation commands.
A spokeswoman added to BBC News: "We will continue to work with vendor partners that have gone through our security and privacy review process and audio review will take place on protected machines."