And a cow's moo in French is appropriately meuh.

I love the bilateral butterfly symmetry.

Hey, I've heard plucked guitar strings called a twang. (That depends on how you're plucking)

I've seen a concertina's sound described as a honk. (A pleasant honk, which seems like an oxymoron to me) Isn't there a better word for that wonderful instrument?

Margarita