Frogs and Toads have a noticeable external eardrum or tympanun,
located just behind each eye, with no outer ear like humans.
This conducts the sound directly to the hearing structures
just behind. These eardrums are usually disguised with the
colouration of the skin.
Frogs don't use hearing to locate prey or danger, but listen
to the other warning calls or mating calls of other frogs.
When a frog comes across a threat they will call to warn other
frogs of the danger. But hearing is mostly used in mating
and territorial activities.