Google knows everything about your past. It knows the location of your previous vacations, the questions you orate, and the pitch of your voice. It's a little creepy.

If you are slightly paranoid, you have good reason. Fortunately, you can delete your Google history by reaching www.history.google.com, which has all your random questions, and choosing which items you want Google to delete. Or, you can listen to how your younger self sounded and complain about much higher your voice was.

Source: http://qz.com/526545/googles-been-quietly-recording-your-voice-heres-how-to-listen-to-and-delete-the-archive/