Sound poems

I spent some considerable time this year explaining "what is poetry?" to undergrads. No, it doesn't have to rhyme, it doesn't have to have a narrative thread, etc etc - but does it have to make sense? In fact, does it even have to use words? Seahorses and Flying Fish had my class in hysterics, and I still can't decide if I think it's poetry. I like multi-media work, so this is interesting in that it juxtaposes image and sound, but....well, there are lots of buts. In some ways it's closer to music - perhaps.