Secretly recording audio is illegal in many (but not all) jurisdictions, including California. However, just because Google isn't recording you to target ads do

Secretly recording audio is illegal in many (but not all) jurisdictions, including California. However, just because Google isn't recording you to target ads doesn't mean no one is. A fair number of people are claiming they've been targeted with ads seemingly based on information that could only have been obtained through audio recording. But so far no one technically sophisticated has, and so these claims never seem to involve narrowing it down to a specific device, or checking the devices for malware or suspicious apps.