Scientists had thought that the Gardiner's Seychelles frog—at 11 millimeters among the tiniest in the world—was deaf because it doesn't have a middle ear, a critical component of hearing that's found most land animals.
The middle ear contains three small bones called ossicles that connect the eardrum to the inner ear. When a sound wave hits the eardrum, it moves back and forth, causing the ossicles to move and send electric signals to the brain, which then registers the signals as sound. (See "World's Loudest Animals—'Power Saw' Cricket, More.")
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