Replying to Physics project

I'm doing my last semester and I have a big physics project to do over the course of that semester. In teams of 5, we have to work on an experiment. Something that has multiple variables that can be tested, like say, how come different musical instruments sound different even though you play the same note (and then you study the waves of different notes on different instruments ans chords and whatnot). It can be related to mechanics, electricity, magnetism, or waves. Any ideas ?