I must confess, I have never actually heard the words 'gyre' and 'falconer'. I assumed they could be pronounced in such a way that it would sound like a rhyme. In my head, they both were pronounced like 'hear'. Likewise, I assumed one could pronounce 'world' and 'hold' in such a way that they could sort-of rhyme. In my head, 'hold' was pronounced 'held' and 'world' was pronounced 'weld.'

http://www.youtube.com/watch?v=OEunVObSnVM

Apparently, this is not the case. Oops.