I was watching Inside Natures Giants on 4OD and when it came to investigating the larynx they forced air through the rather large throat and and it made this strange low gargle.

You can kind of get the sense of what I want on this youtube clip. Towards the end of each end of the roar you can hear deep gargling vibrations, almost flemmy sound. I might be able to re-create this sound, need a long hose or something, but been looking at youtube videos for ideas.

Hum……..where to find a drum :S .

how about making my own ???

Just need some sort of base.