What's that noise? It’s a drone! It’s a buzz! No, it’s a cicada! Cicadas emit one of the most distinct sounds of the animal kingdom—of the insect group, anyway. The song of the cicada is a reverberating noise that’s hard to describe and even harder to re-create.
Where does it come from? “Secrets of the cicada’s sound,” 2013 research provided by the Acoustical Society of America and shared by ScienceDaily, describes the sound as well as the work that a team of U.S. Naval researchers has been doing to demystify the subject: “Their analysis shows that the insects manage to produce their incredibly large sound because they have a unique anatomy that combines a ribbed membrane on the torso that vibrates when they deform their bodies.” In other words, it’s not vocal cords making that cicada sound.
ScienceDaily shares Derke Hughes’, a research engineer at the Naval Undersea Warfare Center, description of this process:
"If your body were like that of a cicada, […] you would have a thick set of muscles on either side of your torso that would allow you to cave in your chest so far that all your ribs would buckle inward one at a time into a deformed position. Releasing the muscle would allow your ribs to snap back to their regular shape and then pulling the muscle again would repeat this. The cicada repeats this cycle for its left and right sides about 300 to 400 times a second."
It’s a unique system of noise-making, and the result is a phenomenon we hear echoing across the landscape once the soil warms up and the cicadas emerge each year, which usually occurs in May or June.
It’s not just the droning, though. According to the U.S. Geological Survey, “Cicadas make a variety of sounds, including very loud buzzing sounds. The males have tymbal organs that include rib-like bands on a membrane that can be vibrated very rapidly by a special muscle. The sounds include courtship calls and squawking sounds when the cicada is handled or disturbed.” If you’re curious, you can hear an audio recording of the sounds of cicadas here.
Cicada calls are hard to miss. They’re the soundtrack of so many Southern evenings. You’ve likely been familiar with them for a long time, but now you know exactly how these insects make the sounds we associate with our Southern summers.
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Have you ever wondered about the song of the cicada? Keep an ear out—you’re sure to hear the telltale cicada drone if you step outside during the warm months.
Source: Acoustical Society of America (ASA). "Secrets of the cicada's sound." ScienceDaily. ScienceDaily, 30 May 2013.