There is something to be said about limiting the assault on the senses with a portfolio. I find that a lot of audio demo reels(especially from pro studios etc who have a bit more budget) bamboozle you with their interface, and the audio (what they are actually trying to ‘sell’ you) gets lost cause of bad design or you you simply don’t listen to it properly ’cause your using your eyes and your ears.
So equating this to an art portfolio: don’t do music. If you have to, keep it very, very simple and very low. Use simple unintrusive sounds for menus (nice to know that a selection has been made) and that should be all you need. Obviously, any AV stuff should be as good as possible, simply cause bad audio will weaken the impact of your visuals and that is never desirable when trying to sell your stuff… so again, if it aint right go without audio.