How Do Cicadas Make Noise? (In Slow Motion) - Smarter Every Day 299

Hey, it's me, Destin. There's a story that I've been trying to tell for a very, very long time, and I tried to tell it back in Peru in 2012, and I failed. Today, we're going to tell that story, but we got to go back to Peru first.

Hey, it's me, Destin. Welcome back to Smarter Every Day. Stop and listen for a second. You hear that? If you live anywhere but Antarctica, you have those near you. They're called cicadas. I happen to know an entomologist. His name is Phil Torres. We're here at Tamo Plata Research Center. And Phil is going to explain to us what exactly is causing that noise.

[P] So there's a couple of things going on here. There's one part that is called the tymbal. So this is where it's like the top of a Snapple bottle. If you click it, a lot of times it's going to make a noise. However, what's really cool about these guys is this bottom part of its body is actually hollow, and that serves as a resonance chamber. So what we're going to try to get on the high speed is to see how fast it is that this is actually vibrating to make that noise.

[D] Sweet. So I've got the high speed set up at 3,000 frames per second, but I'm not good enough to focus on this. So that's what Jeff's doing. Jeff is the photo tour guide here at Rainforest Expeditions. We struggled to try to get the cicada in the right spot for a long time, and we never could quite get the shot. We couldn't tell if it was because of our frame rate or if we just didn't know where to look on the cicadas. I think that thing's opening and shutting in less than a millisecond.

[P] No way. It actually ended up being six milliseconds, but more about that later. I want you to understand the reality of cicadas in Alabama right now. As you've probably heard by now, there's two different broods of cicadas. Some pop out after 13 years, some pop out after 17 years. I think we have the 13-year brood here in Alabama, or both, I don't know. But what I do know is they're absolutely everywhere. You'll be driving down the road and a cicada will just land on your windshield wiper and hitch your ride, in this case, for five miles, which blew my mind that he was able to hang on that long.

I went to one of my favorite restaurants the other day. There's just a cicada on the floor. The people that own the restaurant, they keep a very tidy restaurant. But if the door opens for any amount of time, you're just going to get cicadas. It's just going to happen. They're like ants now. Notice. These are coming out of the gutter? Just everywhere.

This particular tree, for some reason, look at all the holes in the ground where they've been coming up. Oh, my goodness. That's nuts. They must come up, crawl up the tree. What tree is this? It's a cicada tree. And then these are all their... I guess they're called shells, but look at this. It's nuts. It doesn't smell great. It's inches thick. It's crazy. That is a lot of cicadas.

So to be clear, these cicada exoskeletons are the result of the cicadas, which have been living underground for years and years and years, depending on what brood it is, 13 or 17 years. They've been living underground, sucking sap and nutrients off of tree roots. They come up out of the ground, and then they go, they hang on a tree, they shed their exoskeleton, they have these wings, and then they go try to sing and mate.

And what we've been trying to show with that video in Peru, which was this slow motion camera right here, we were trying to show what's making the noise, like what part of the cicada is so loud, that tymbal that Phil was talking about. Now, the fact that this camera couldn't show it is a significant thing because this goes thousands of frames per second. So today we're going to try to continue telling the story with this camera, which can go 100,000 frames per second. But the problem is we need a cicada, and I have misplaced the one I had here, so we have to go cicada hunting.

This is George.

[G] Hello.

[D] It's time.

[G] It's overwhelmingly. We have to.

[D] We have to do it.

[G] Well, we have to try.

[D] So here's the deal. It's 2024. The cicadas are out in force. Two broods are out. My understanding is only one brood is here in Alabama. I don't really know all that.

[G] It's a big brood, though.

[D] It's huge.

[G] I don't remember it being this loud.

[D] It's crazy. We're here. We're going to get out of the truck and just let you hear this. It's insane. We're on a wildlife refuge, which is why I can film and drive. So how would you describe this? There's two sounds, right?

[G] Yeah, there's a high pitch clicking.

[D] Yes.

[G] And then somehow underneath it, there's this low thing that I describe as when a subway train is pulling into a station before it gets there, when it's still 100 yards down the tunnel and you can hear it coming.

[D] It's like the slipping of the metal wheels on the track.

[G] Yes, that's exactly what it is, exactly.

[D] So I'm looking at this truck.

[G] I've been trying to think of what is that sound, and that's exactly it. You just connected it for me.

[D] I think this... this might be a wildlife refuge, guy.

[G] It is, it's US government.

How's it going?

[M] Hey.

[D] Are you all wildlife refuge people?

[M] Yes, sir.

[D] I'm making a video. Is that okay?

[M] Yeah.

[D] I'm here making a video about cicadas?

[M] Oh, okay. What's it? I'm Destin. Okay.

[M] Hi, I'm McKenzie. Nice to meet you.

[D] McKenzie. Nice to meet you.

[T] Tyler.

[D] Tyler.

[M] We're Pathways intern for the Fish and Wildlife Service.

[T] Us Fish and Wildlife Service.

[D] So you're interns?

[Both] Yes, we are.

[D] What can you tell me about the cicadas?

[M] They're loud.

[T] Cicadas, they're loud and obnoxious. I know there's different types of groups of cicadas that are not hatching but coming up. I don't know if this is the 13 to the 17-year cycle, but I think they're all coming up around the same area at the same exact time.

[D] Where is they the loudest?

[T] They'll be around the edges of the trees. That's what I think anyway.

[M] They're louder right here than if you go deep into the wood.

[T] Deep into the wood, yeah.

[D] Really?

[M] We've noticed on outside edges, you would think if you go into them, it'd be louder, but we've noticed that they're loud on the outside.

[D] Can you write us a cicada permit so we can go cicada hunting on you?

[M] I cannot.

[G] This is an app, and it tells you the decibel level, and you can do all sorts of things. See, it'll start doing data. I think that top band, the high band, is the high pitch one. Then the very consistent one is the thing that I,

[D] The subway car sound?

[G] The subway car sounds. And now our voices are going to mix in with it. So if we let it rip for a second. What I want to know is what causes the top one? What causes the bottom one? Is there two different animals doing one male and one female? Is there a call and response, or is it just two different creatures? Is it one creature making the two different noises at once?

[D] So there's clearly two sounds going on here, and we got to figure out why. And one of the smartest people I know when it comes to sound is Gordon Mcgladdery. He makes all the slow-motion sound and the music for Smarter Every Day. To top it all off, the first time I ever collaborated with Gordon, he wrote a song called Cicadas Waltz, which actually incorporates generated the sounds of cicadas into the song. I made a slow-motion video of bottles blowing up, and Gordon made a song for that video. So let's ask Gordon what's going on.

All right, this is Gordon, Shell in the Pit. He does all the audio and the music you're going to hear later in this episode. Gordon wrote it. Did you get the file I sent you?

[G] I did.

[D] Can you open that, please?

[G] Yes.

[D] Out in the field, we saw two frequencies, and I want to show it to you. What is this?

[G] This is a spectrum analyzer.

[D] Spectrum analyzer. That stuff off to the right is us talking.

[G] Yeah, totally.

[George from audio recording] I wish I knew what frequency that was. Are you screen recording?

I'm recording the data.

[D] All right, so can you show us what's going on over here to the left?

[G] Okay, we have two distinct frequency bands. One is between 1,000 and 1,200 hertz, and then the other is roughly 3,000 to 9,000 or 10,000 hertz. If we listen to them separately.

[D] So that's what George says sounds like a subway car to him. One of the teachers around here said it sounds like the Star Trek teleporter.

[G] Yeah, it's cool. The other one is, I think, the one that most of us would recognize is like, yeah, that's cicadas.

[D] So here's the question. What's the other one? What's the streetcar sound and thing?

[G] My guess is that these are not two separate insects. I think that would be the first thing we jump to is like, these are two different animals, but we can see that they are both happening all the way across. My second guess is that the cicada is resonating in two frequency bands, which is interesting because that requires two sets of vibration of some kind. I bet it maths out, you'll see that they're somehow related.

[D] Using the information we got from the Wildlife Refuge interns, we found a clearing that was about 100 yards away from the Tennessee River, and we found the mother load of cicadas. We need a net. Why do we not have a net?

[G] There's going to be one right here.

[D] Oh, they're doing it. They're making other cicadas. Oh, dude, can I see that?

[G] Yeah, do it.

[D] This seems to be the point. Look at this. They're mating. What are you doing under there?

[G] Well, two cicadas love each other very much.

[D] This is how they make baby cicadas. There's a question I have. If these things come out every so many years, then what happens? Do they plant eggs?

They're connected, dude.

[G] Yeah.

[D] Got one.

[G] There you go.

[D] Get in there. Get in there. Two. Don't eat that.

[G] We have four.

[D] We've got four cicadas. Oh, they're loud.

[G] I think we got to go do slow-mo before we lose the sun.

[D] Yeah, let's go try slow-mo.

[G] Okay.

This cicada hunting trip took longer than expected, so we rushed back to try to beat the sun in order to get at least one slow-mo shot before the end of the day.

Hit it.

All right, we're going to see something.

[G] You can see it.

[D] I can see it, yeah. You can see it moving, yeah.

Oh, dude, we're going to see it.

[G] Holy cow.

[D] We're totally going to see it. So that's the tymbal. This is 25,000 frames per second.

[Both] Ohhh!!!

[Destin laughs] It's like a reed, and this is like hollow.

[G] Yeah.

[D] Okay, the bad news is I found a 10-year-old jar of jelly in my fridge. The good news is it has the exact type of lid I need because it's the same type of lid that was on this jar of jalapenos.

Okay, so look at this. When you click this thing like this, it's pretty loud. But when you put it on a resonant chamber, I don't know if you can hear that, it's a lot louder. That's how the abdomen of a cicada works. It's hollow on the end there. And so as the tymbal is vibrating, it is resonating in the abdomen down below, which I think is fascinating.

Now, imagine instead of just one tymbal in a resonant chamber, imagine if we had a can like this and we had one on one side and one on the other. It would be much louder. But it's not just louder because there's two tymbals.

I've read some papers and they all have very interesting things to say. It looks like because you have a tymbal on each side of the hollow cavity abdomen, that it's something called constructive interference, which is interesting. Now, the cool thing about the cicada right here is if you look at a cross-section of the hollow abdomen, you've got a tymbal over here, you've got a tymbal over here.

So that acts like the two cans like this, only they're not popping like this. They're folding back and dithering or whatever we're going to figure out on the high speed. So when they're producing sound, they're being pulled by muscles like this. And because they're opposite each other and the muscles can control them at exactly the same time, you can create a sound wave from each at the same time, and they hit and add together and you get a much louder sound. I think that's amazing.

And the thing that's really interesting to me is it's not a click. Like these jars, like these jars, like I was expecting, there seems to be a lot more going on than just one simple click. Your face, dude, is like, what?

[G] I know that-

[D] Look at it.

Okay, there he goes. We were at 25,000 frames per second. If we knew the frequency of the sound, we could calculate the...

[G] The vibrate.

[D] Yes!

We ran out of light, so the next day we went and barred a net from a gas station and we went cicada hunting again.

So I got a cricket bucket. They should be able to go in there without getting cooked. So it's an open top. Open top. We got to transfer our most important message to this, I think. "Cicadas do not eat."

[G] You get it?

[D] Yeah.

[G] Yeah, that's one.

Get it.

[Destin laughing and giggling]

[D] He's loud.

[G] Oh, he missed. That was nice. That was backhand.

[D] That was backhand.

[G] That was backhand. That was impressive. That made up for a couple of the other...

[D] The couple were pretty bad.

After we collected all of our cicadas for the day, we put them all in our little trap. We remembered not to eat them, and then we headed back to set up the slow-mo. This time, we were going to try a shot at 99,000 frames per second.

Get it.

[G] Did it.

[D] Yeah, we got it.

Then we ramped it up to 110,000 frames per second. If you look at several of the clicks over a sequence, if you realign it so that you can compare three different ones, you can see that the depth of the contraction of the muscle that's controlling the tymbal is different on different strokes.

We wanted to see the tymbal really, really close at really high speed, so we switched from the 100-millimeter macro to a 65 MPE, which is basically a lens with a built-in macro extension tube.

I don't think the muscle is pulling and relaxing.

[G] It's pulling and it's getting each one of these strands, essentially. And so it looks like it's going dung, dung, dung, dung, dung.

[D] Pull vibrate, pull vibrate, pull vibrate. I think that's what's happening.

[G] But I think it has to overcome the force of each of the mechanical the stress force of each of these.

So then that's what each one it goes. So it pops, pops, pops.

[D] I'm imagining an arch, and you have to buckle each arch. And it's easier to buckle a longer arch than it is to buckle a shorter arch. So if you pull from one side and you start pulling in, it's like a progressive buckling.

Progressive buckling, is that a thing? A direct approach to progressive buckling design. In case buckling occurs due to progressively increase...

It's intentional buckling.

[G] Progressive buckling.

[D] Progressive buckling.

We're just making words up.

[G] We are, but somebody else has used them.

[Destin Laughs]

[G] In a scientific...

[D] In a scientific paper.

Okay, so we can clearly see what's happening mechanically, but it's not obvious how this is translating into sound. It's time to go show this to Gordon and see what he thinks.

[G] It looks like it's caving in. It looks uncomfortable.

[Destin laughs]

[G] One, two, three. One, two, three.

-One, two, three. One, two, three. One, two, three. so it's three, four time or triplets, however you want to map it out.

[D] So if you look at the tymbal in slow-mo, we have three things happening. It's like you've got all these striations or these pleats, and they're buckling progressively as it goes up, right? But as they buckle, they each wobble.

So it's like, buckle, wobble, wobble, buckle, wobble, wobble, and that happens all the way up, and then the whole thing resets.

So now we can look at the spectrogram with a new understanding. We have this mechanical device that's doing multiple actions, and then we have this spectrogram that has multiple frequencies.

My guess are that the wobbles correlate to the higher frequencies on the spectrogram, and the buckling, the progressive buckling, is the subway sound. But I don't really know, so I don't want to come down definitively until I've had time to do a detailed time analysis and measure the delay of each mechanical action.

Furthermore, as millions of cicadas interact in and out of phase in a small area, who knows what that does acoustically. I think it's so cool that years ago, Gordon wrote a song called Cicada's Waltz without us realizing that the mechanical tymbal of a cicada works on the same time beats as a waltz.

I think that's awesome.

[soft guitar music starts]

We have a problem. We have all of these cicadas left that we can't eat. The way I want to release them incorporates the sponsor for today's video. Dan at Ridge said, "Destin, we would love for you to incorporate our products into your video in some way."

I'm going to test the relationship right now. I don't think they were thinking beauty shots with cicadas. I'll tell you about Ridge as these cicadas are flying away. I think that'll be fine.

Oh, get it, get it, get it, get it triggered.

[G] I did it.

[D] All right, we're going to see. This is my wallet. It's called a Ridge Wallet. I'm going to tell you why this is the ideal solution for carrying stuff in your pocket, like credit cards, money, stuff like that. I love this thing. It is my everyday carry.

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You can also personalize certain models by putting your name or the name of somebody you're giving it to as a gift on there. Ridge has a new type of wallet that will stick to your phone with MagSafe, which is awesome.

But the question is, will cicadas stick to the wallet? If you don't love it, after 99 days, you just give it back. They give you your money back. It's like either love it or you don't. If you don't, you get your money back, so there's no risk.

But you will love it because it's the answer. I genuinely think it's the answer, for me at least. Go to ridge.com/smarter. When you do that, I have asked them if they would throw in an AirTag money clip because I think it's awesome, and it helps me find my wallet.

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If you want the free AirTag money clip, just add it to your cart, and then at checkout, use the promo code smarter, and it'll take that cost away. That lets them know that you came from this video, which hopefully would incentivize them to sponsor Smarter Every Day in the future. So you'd be doing me a solid.

Plus, you'd get the coolest wallet in the world. I genuinely believe that, so ridge.com/smarter check it out. If you're an academic and you think this cicada tymbal footage would be helpful for you, reach out.

I would love to communicate about that and see if we can figure out some of the stuff that's going on here. The thing I haven't seen described in the literature so far is this wobbling that we're seeing here.

So, yeah, reach out. Let's write something up. Also, I just want to say I'm very happy to hear that people that are patrons of Smarter Every Day seem to be happy with the fact that they were able to download the high-res version of the 2024 Eclipse photo. Thank you for supporting on Patreon.

If you've ever considered doing that, it's a good time. You can download that really cool photo. And I'm grateful. Thank you for supporting Smarter Every Day at Patreon.com/smartereveryday. Thank you very much.

Feel free to subscribe or sign up for the email list if you're into that sort of thing. If not, no big deal. I'm Destin. You're getting Smarter Every Day. Have a good one. Bye.