How minute sooglossid frogs hear without a middle ear

Gardiner's Seychelle frog, one of the smallest terrestrial tetrapods, resolves an apparent paradox as these seemingly deaf frogs communicate effectively without a middle ear. Acoustic playback experiments conducted using conspecific calls in the natural habitat of the frogs provoked vocalizations of several males, suggesting that these frogs are indeed capable of hearing. This species thus uses extra-tympanic pathways for sound propagation to the inner ear. Our models show how bone conduction is enhanced by the resonating role of the mouth and may help these frogs hear.