Your voice
Record 10 to 15 seconds on your phone in a quiet room, ideally inside a parked car so it has the same small, dry sound as the scene. Don't read the script lines; say something in three moods so the model hears your range:
(calm) "Just driving around LA today, grabbing a coffee, pretty chill afternoon."
(confused) "Wait. What? Are you serious right now?"
(panicking) "Hey! No, no, no, stop! What are you doing?!"
[tag your voice clip here]