If koalas have any reputation at all, it's as quiet, cute marsupials that spend all their time eating eucalyptus. But male koalas unleash loud, deep yells that sound like the mating call of some massive beast. That's exactly the point.
Electro-Harmonix, producers of the BIG MUFF, make some of the best music effects boxes around. And the new Voice Box is amazing: it will automatically harmonize with whatever you throw at it. See for yourself.