1Hey, it's Esther.
2Growing up, I would hear this chirping sound outside.
3Maybe you've heard it too.
4...
5I knew it was made by insects like crickets,
6but I never thought much about it.
7Then one spring, grown-ups started making a big deal about something called a cicada.
8There were going to be lots of cicadas that summer.
9And sure enough, I heard them.
10They made a sound so loud it filled my entire neighborhood.
11But the strange thing is, I never saw the cicadas.
12I was so curious about them,
13and someone named Elvia is too.
14Let's give Elvia a call now.
15Hi Esther.
16Hey, Elvia.
17I have a question for you.
18How cicadas make so much noise?
19That's a great question!
20Once I finally found out that cicadas look like this,
21I wanted to know the same thing.
22How does this small insect make such a huge noise?
23I mean, people can just open their mouths and let sound out.
24We can also make sound by snapping our fingers
25or clapping our hands
26or stomping our feet.
27But insects' bodies are very different from ours.
28They have parts like antennae,
29six legs,
30and sometimes wings.
31Some insects have mouthparts shaped like pinchers
32or curled-up tubes.
33If we can use our bodies to shout and snap and clap,
34what do insects do to make sound?
35To figure this out, let's listen and watch as two insects make sound.
36First, here's a grasshopper.
37And second, here's a cricket.
38Now I'll play them both at the same time without sound.
39I'm curious what you notice.
40How do you think these insects make noise?
41Maybe you noticed that these insects are moving parts of their bodies.
42Like this grasshopper's legs,
43they start moving up and down really fast.
44The cricket's legs don't seem to move much,
45but its wings move really fast.
46And when the wings stop moving, the sound stops too.
47Grasshoppers and crickets move body parts back and forth to make sound.
48But they use different body parts: legs and wings.
49Take a close look here at the inside of this grasshopper's leg.
50It's got this bumpy ridge.
51There's something similar on this cricket's wing.
52Let's look closely here.
53Up close, you can see it's actually lots of tiny ridges.
54Grasshoppers and crickets rub these bumpy ridges back and forth against other body parts to make noise.
55It's kind of like the ridges on this instrument.
56When you rub a stick across them, it makes a noise too.
57Only these insects move their body parts even faster.
58Now see what you notice about this cicada as it makes noise.
59I don't see its legs moving,
60and its wings don't move much either.
61But do you notice how its body is moving?
62When this person gently lifts the cicada's wing, being careful not to hurt it,
63you can get a better look.
64Watch this part here.
65See how it shakes back and forth?
66This is a special body part called a tymbal.
67There's a tymbal under the other wing too.
68The tymbal is making sound as it moves.
69But unlike the grasshopper's legs or the cricket's wings,
70the cicada isn't rubbing anything against it.
71Instead, a tymbal works more like a metal cap from a container.
72When you push down on the flexible center and let it spring back,
73it makes clicking sounds.
74...
75When you saw the cicada's body moving,
76it was flexing muscles that move its tymbals back and forth.
77That makes part of the tymbals bend and spring back, like the metal cap.
78Imagine for a moment that you have tymbals on the sides of your belly.
79See how fast you can flex your belly muscles to make your tymbals move.
80Kind of tiring, right?
81Well, a cicada can move its tymbals back and forth super fast.
82Fast enough to make 300 to 400 clicks in one second.
83All those clicks blend together into one big buzzing noise.
84Cicadas are among the loudest insects on Earth.
85And we usually don't hear just one.
86That sound on a warm summer afternoon is dozens and dozens of cicadas.
87They sync up the rhythm of their clicks to make an even bigger sound.
88It's like how the crowd in a stadium can clap and stomp together to make a thunderous beat.
89Or how the singers in a chorus can fill a room with music.
90A group of cicadas clicking in sync can make a sound that fills a forest
91or your neighborhood.
92Scientists even call a group of cicadas a chorus.
93So in summary, cicadas and some other insects use different body parts than we do to make sound.
94Grasshoppers use their legs.
95And crickets use their wings.
96And cicadas use special body parts called tymbals.
97These insects move their body parts back and forth really fast to make sounds.
98That's all for this week's question.
99Thanks, Elvia, for asking it!