BLEATING TREE FROG Litoria dentata (Keferstein, 1868)
A small 4 cm frog found along the coast and ranges of NSW, and south east Queensland, it is found in most available habitats.
Common around human habitation this frog is also often found around swamps and lagoons.
This frog breeds in summer after thunderstorms and general rains. The call is a distinctive long wavering bleat.
Large numbers of this frog calling can produce a deafening sound.

The above was from the book Australian Reptiles and Frogs by Raymond Hoser and now available on a fantastic CD-Rom along with a vast amount of other information, papers and the like on reptiles, frogs and other wildlife.