It is a very small frog with a very distinct loud call. It is sometimes known as the Peeping Whistling Frog which is a pretty good description of its call. The call is series of 5-25 high pitched whistled peeps. Each series of peeps lasts for 2-3 seconds. The main frequency of the peeps is between 3kHz and 4kHz and each "peep" actually increases in frequency during each call, although that isn't audible unless you slow the call down quite a bit.
The call is quite loud for such a small frog and carries well in the rainforest.
Here is a spectrogram of the call of this species -
Unfortunately, I never was able to see this species while in Queensland although I heard them calling on a number of occasions.
Here is an individual calling from the Daintree Rainforest near the Jindalba Boardwalk on wet evening in January 2015.
© Chris Harrison 2015