> When Voice & Audio Activity is off, voice searches will be stored using anonymous identifiers. This information won't be saved to your Google Account even if you're signed in.
Huh. Pretty sure this wasn't available 6 months ago or so when I set up Google Now. You needed to opt in to search and app history to use Now, which included OK Google, or something.
https://www.google.com/settings/accounthistory/audio
> When Voice & Audio Activity is off, voice searches will be stored using anonymous identifiers. This information won't be saved to your Google Account even if you're signed in.
https://support.google.com/websearch/answer/6030020