The microphone of your mobile device never records any audio. It merely processes audio within the device's proximity into a string of code. We call this an audio fingerprint, which allows us to match against our database of audio fingerprints of popular audio-based content and advertising.
Such data looks like this: user_id: 1234,matched_content: ABC radio ad, audio_fingerprint: 265523236267, timestamp: 6:13 PM