Google stores your audio for recognition

You may not realize this, but every time you ask Google Now a question, Google makes a recording of it and keeps it stored in its vast trove of information it stores on you device

You can find your archive of Google Now audio files by logging into your Google account and then opening up audio activity . If you’ve turned on Google Voice and Audio Activity, you’ll see a list of all the voice commands you’ve entered into Google Now along with buttons next to each one that will let you play audio of them. You can also delete anything and everything you want to.

(In layman's terms , a session is created i.e for faster access of data etc. ,like a cache memory -it stores temporary information about client for faster retrieval of data )

When you use audio activation commands, such as ‘Ok Google or touching the microphone icon, your private Voice & Audio Activity stores some voice and other audio to your account,” Google explains. A recording of the following speech/audio, plus a few seconds before, will be stored. This helps Google recognize your voice and improve speech and audio recognition in order to give you results faster and with fewer hassles.

You can turn off Voice and Audio Activity on your Google settings although this won’t stop Google from recording and archiving anything you ask Google Now. Instead, your voice recordings will be made anonymous without any direct links to your Google account.