Female Mediterranean tree frogs which are ready to mate approach a loudspeaker, 2 metres distant, from which mating calls specific to the originate. Differentiation tests show which sound characteristics play a part in the acoustic orientation. Given a choice of natural mating calls, which have differring characteristics depending on temperature, the females show a preference for those calls with higher temperature characteristics. The females also react to electronically simulated mating calls. The reaction of the females to the synthetic mating calls also depends on the repetition rate of the impulses which build up the calls.