I just upgraded to Google Assistant on my phone, and it overheard me ask a colleague a question. It then searched it to try and find the answer. Does Google Assistant listen to everything? I definitely did not say "ok google". Even with a keyword, doesn't that mean it's listening to everything until you say the phrase "ok google" and that triggers the search? Is there any way to control when it listens or executes a search?
Yes, it does listen to everything but only activates and streams to Google on keyword activation. It has to listen all the time to trigger itself.
Once you say the keyword it will stream a few seconds before you said 'Ok Google' listen to your question then send the data to Google for an answer.
All this data is logged as well, here is a guide to find and delete voice recordings: https://qz.com/526545/googles-been-quietly-recording-your-voice-heres-how-to-listen-to-and-delete-the-archive/
I recommend you to not use Google Assistance since exists vulnerabilities or security problems.Google Assistance is recording your calls and can use google search engine to detected you.
Example: Talking to my wife about "dogs" and Google Assistance was recording me. After the call ended I opened the browser and i have in google box the word "dogs". https://www.howtogeek.com/319490/how-to-disable-google-assistant-or-at-least-take-its-shortcut-back/