Do you mean their diaphragms...? They can form words using their mouths, just not like humans can obviously. All your diaphragm does is make the noise-You shape it.
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Nope nope nope nope... Wrong [spoiler]wrong[/spoiler][spoiler]wronghgggggfv[/spoiler] [spoiler]WRRRRROOPOONNNNGGGG[/spoiler]