does a program that does this exist?

[neofemme]

im looking for some program that uses concepts of audio focus in osx. basically something that when i hit a hotkey keeps the window i have open at 100% audio but changes all other applications that are using my audio output to something like 30%.

Thanks

[DeltaMac]

You need to define what you mean by 'audio focus'
Do you mean Full volume with the window in focus, but other windows/apps would still be playing audio, but at a reduced volume?
Quicktime player can be set to play audio in all open windows, or only the front-most windows.

Audio Hijack might do something similar to what you want.
http://www.versiontracker.com/dyn/moreinfo/macosx/16382