During Story Mode you will pretty early on unlock the Audio Scanner tool. Throughout the game there will be numerous points where you will have to use the scanner to listen to peoples conversations. There are way more than 20 conversations to listen to throughout the game so don’t fret too much about this. Each of the Gang arrest Police challenges will require you to use the audio scanner and listen in to a particular conversation, the one that is scrambled. Before listening to the scrambled one be sure to hover over each of the other conversations before unscrambling the one you’re meant to listen to.