Frogs can hear using big round ears on the sides of their head called a tympanum .
Tympanum means drum. The size and distance between the ears depends on the wavelength and frequency of a male frogs call. Well, actually, frogs have special ears that are connected to their lungs. Children's BBC in England are now producing a third series of the interactive TV game show Sub Zero. Children taking part from home can play Net Detectives on the website .