This is one of the first recorded sounds of the Pobblebonk.
Being "pobblebonk" and "didgeridoo" onomatopeic they have much in common. They are also very different as the first is a frog and the second a musical instrument. We believe that we have rectified this asymmetry not by finding a new species of frog and calling it a didgeridoo but rather finding a new musical instrument and calling it a pobblebonk, as its sound is to pobblebonk as the sound of a didigeridoo is to didgeridoo.
Pobblebonk is indeed the unlikely name of a frog that lives in south-eastern Australia. It makes various interesting noises. Amongst the pobblebonks is the Southern banjo frog, Limnodynastes dumerilii insularis, which can be found in the south-east of mainland Australia and in Tasmania.
Frogs in general employ an unusual mechanism to create their croaks, squeks, growls and other sounds. The volume of these sounds can be very loud, due to inbuilt amplification mechanisms, and also very deep, belying their smallness.
What is it?
The Pobblebonk is a musical instrument that shares some of these characteristics - in particular it is a small instrument that makes deep sounds that recall those of the pobblebonk frog, both in timbre but is also in the way that they are produced. The Pobblebonk is a lip reed instrument where the lips play the role of the larynx of the frog.
The recorded sound is probably more pobble than bonk, the bonk being the sound that gives the Pobblebonk its other name, Southern banjo frog. Maybe the pobblebonk instrument can also recreate that sound...