Looking for Car Audio Software Ideas

With the intent of broadening my technical horizons, I took an "introduction to Java series" of lectures at work. While I thought of some work applications, I more immediately thought of car audio software. I still need to get setup at home, but I have the tools in place at work to start dabbling.

What are some calculations/modeling I would find useful for increasing understanding of the field and also for install application?

Thanks.

This would be fun if you need help with Java let me know.

Here are a few IDE's that you may want to try but, not all are free.
NetBeans
JCreator Pro
Eclipse

Checkout the Java api
http://docs.oracle.com/javase/8/docs/api/
Some Tutorials
http://www.tutorialspoint.com/java/index.htm