Cicadas are number 5 on The Most Extreme Loudmouths. They are the loudest insects in the world. They can be as loud as a chainsaw at full throttle. They make this exceptional noise with a pair of ribbed membranes at the base of their abdomen. By contracting and releasing internal muscles, the membrane flexes. Smaller species sing in such a high pitch that it can't be heard by humans. The noise is actually mating call belted out by males and each species has its own distinctive song that only attracts females of its own kind. They must protect themselves from the volume of their own singing, that's why they retract a tendon that creases their eardrums and prevents damage.
- If following the countdown of extreme Loudmouths, here is a link to the next contender, for which wearing internal ear muffs would be a real problem, as it uses sound to see in the dark.