The article mentions audio which may not be limited to just music:And why would I play music in my ears and blast navigation directions to the car audio. I would obviously do it the other way around?
Could the other audio perhaps be a phone call in cars that don't have bluetooth?In another example, Mac Otakara suggests a usage scenario in which an iPhone could be connected to a car as well as wireless headphones, transmitting GPS directions to the in-car audio system and audio to the headphones.