This is so incredible I can hardly stand it. Check out this clip from Channel 4's Inside Nature's Giants, wherein researchers pass compressed air through the larynx of a dead lion to demonstrate how it modulates the tone of its roar.
You'll want to fast forward to 11:36 (the lazy among you can just click here). Make sure you full screen it and crank it up to 720p so you can stare in awe at all the larynx-groping goodness you're about to witness. You also want to make sure you watch until around 13:00; it takes a little fiddling, but after a few adjustments the team is able to go from generating indiscernible vibrating noises to producing the distinctively guttural rumble of a big cat's roar.
Via my new favorite tumblr, Fuck Yes Inside Nature's Giants