Controlling Audio and Fade

[eecer]

I enjoy running the Police Scanner app and Pandora when driving home, the problem I have is both apps are always at the same volume so depending on how quiet they are on the scanner the music will take over the audio. I was hoping to find a way to treat the Scanner like the Navigation voice over and when there's a sound coming from the Scanner app it will lower the volume for the music. Anyone know of any way to do this or an app that allows you to show which apps control the volume more?