It's yea, not "yay".
But I was going for the rhyme, in case you must now. It seems it went totally over your head; such a simple little thing.
---------- Post added 2013-01-20 at 02:06 AM ----------
So, this justifies the existence of sound magic, or at least how sound is an expression of arcane. Arcane is math, music is math as well. So it does make sense on that respect, but sound by itself is most likely not magical.
Nonetheless, if sound can be the expression of a magical source, it makes bards plausible; no matter how much it revolts me.