Just recently, I read a magazine article about them. It states that the male cicada is the loudest insect alive, his call coming in at up to 106 decibels--which is louder than a chain saw!
I looked up cicada in wikipedia.com, and this is what it has to say:
Male cicadas (and only males) have loud noisemakers called "tymbals" on the sides of the abdominal base. Their "singing" is not stridulation as in many other familiar sound-producing insects like crickets (where two structures are rubbed against one another): the tymbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened "ribs". They rapidly vibrate these membranes with strong muscles, and enlarged chambers derived from the tracheae make their body serve as a resonance chamber, greatly amplifying the sound. Some cicadas produce sounds louder than 106 dB (SPL), among the loudest of all insect-produced sounds. (This amazing sound has frequently inspired haiku poets in Japan to write about them.) They modulate their noise by wiggling their abdomens toward and away from the tree that they are on.
Only males produce the cicadas' distinctive sound. Both sexes, however, have tympana, which are membranous structures used to detect sounds; thus, the cicadas' equivalent of ears.
End of science lesson. *Grin* The cicadas signal that summer will soon be drawing to a close. August will slip into September and it will be fall before we realize it! I've enjoyed my summer so much--I don't want to think of the cold months ahead just yet!
Picture from wikipedia.