Shooting Down a Lost Drone and why Dogs Tilt their Heads - Smarter Every Day 173

Hey, it's me Destin. Welcome back to Smarter Every Day! I'm in the middle of the woods. My son lost a cheap little drone, and the only way we can figure out where it's at is we are powering it up and listening to where it is. It's really got me thinking about directional hearing.

To bring you up to speed real quick, my sister bought my son a toy drone which, of course, he immediately went outside and flew as high as he could and let the wind carry it off into the woods, way out of sight. All we knew is that it was in a huge section of the forest. Now, problem-solving is an important skill that I always try to teach my children. So, first, I'll let him wander around aimlessly for a bit—of course not finding it—and then I decided it was time to start our little adventure.

First, we all spread out in the woods and got real quiet. We then activated the drone and used our directional hearing to see if we thought we knew where it was coming from. It was super faint, so each walked in the direction we thought it was coming from, and we all stopped, got quiet again, and then reactivated it. At this time, we were a little bit closer, so we felt more confident with our directional hearing, and we moved in that direction.

With three of us, we were able to easily triangulate it even though we couldn't see it, but this is where it got weird. We had absolutely no idea how far up the tree it was. It was like our directional hearing somehow worked in the horizontal plane, but in the vertical plane, it just didn't work. Right now, we've isolated it to this tree, we think, but we're not really sure...exactly where. But we're using our stereo hearing in order to find it.

It's really cool! Son's bringing some binoculars. Look up in the tree. That's where I hear it. It is in that tree. I hear it in that tree.

"Okay, where?"

For you, you see that branch right there, and the branch is covering it up.

"Oh, do it again."

There it is! That's it. Okay, I think we can do this.

"Son, go get a rifle."

So we found it just in time.

"You got it?"

Yeah, do it up?

"You're freaking awesome. Did it come down?"

Safe the weapon, stand by.

"Ah, ah, ah! Get back! Get on the ground! Make sure the weapon's cold. I know we're excited; let's be safe. We did it. We got it!"

Weapon's safe; let's go get it.

"All right, Aunt Briley gave you a Christmas present and then she saved your Christmas present. So that's pretty cool."

That is the power of the directional hearing that our bodies have because if you think about it, one ear to the other, if I have a sound on this side, the sound hits this ear one millisecond before it hits this ear. The higher frequencies are muffled out by the time it gets over here because that sound goes across my face.

We just use that to find this. But you know what I think is interesting? How can you find something? How did you know it was up high?

"I don't know."

I don't either. This is a really good question. Think about it. If there's a sound directly in front of you and you hear it, it's stimulating both of your ears at the exact same time because the distance is the same, right? If you take that same sound and you move it vertically, the same is true. So you can't resolve a vertical position directly in front of you with temporal cues, meaning time. It has to be something else.

It wasn't until I found an experiment performed on the YouTube channel called Scilabus that I understood the answer to the problem. It's called spectral cues. If you think about a sound across the room, it's going to go to your ear and bounce off of your ear and down into your ear hole. If you have a sound from below, it's going to bounce off a different part of your ear and then into your ear hole.

That is going to change the sound before it goes into your body, and your brain has developed this complex algorithm. It has to do with the area of study called psychoacoustics, and it will tell your brain exactly where it is in the vertical axis based on frequency and spectral cues, and that is amazing.

I watched a video on Vivian's channel, Scilabus, about how to test this, and you can do this at your own home, so I would encourage you to go watch her video. But I wanted to do it with my son, so we're going to illustrate this with my son here.

"See, we've got this big setup. What I'm going to do is I'm going to take my hands and I'm going to clap it like this (clapping) and you point to exactly the spot where the sound is coming from. Can you do that? Try it."

"Are you cool being blindfolded?"

"I'm fine with that."

Okay, here's the deal. His brain is calibrated for the spectral cues off of his shaped ear. If we were to pack Play-Doh in the pinna, that's going to change the spectrum that comes down into his ear, and he's not going to be able to calculate the position in the vertical axis. I learned this from Scilabus. Vivian did a really cool experiment—go check it out on her channel.

Anyway, let's do the clappy thing again. So what you'll notice is if we're on the left or the right, he gets it almost every time, but he has a hard time with the vertical axis. He can't even tell if it's forward or back.

"I was clapping right between your legs and you pointed up."

"What?"

Do you realize how awesome that is? Let's just use all the big words. We just derailed the psycho-acoustic filter in my son's brain by negating his ability to use temporal cues because of the position of the sound, but driving him to not being able to trust his spectral cues because we dampened down the pinna, which is the floppy part on the outside of his head, by using Play-Doh. So he couldn't figure out where the sound was coming from. That's fascinating.

The cool thing about this is that dogs don't really do it that well. Have you ever said something to a dog and he kind of does his head like that? What he's doing is he's trying to cheat a little bit. The dog's putting one ear above the other so they can resolve vertical position. That's amazing. They're using temporal cues. They're cheating with temporal cues to try to get something that we get with spectral cues.

I've never thought about this, and the reason that's important is because I have a whole YouTube channel you didn't know about, probably. It's called The Sound Traveler. I have been recording video for years now where I put binaural microphones in my ear, and if you wear headphones and watch the video that I'm recording, it tricks your brain into thinking you're there based on these temporal cues.

"Okay, tell them about the thing we do."

Briley: "So there's a second YouTube channel. It's called The Sound Traveler. We go around the world and we record experiences with binaural audio. I've gone to Thailand and DC. Destin's done Iceland, Germany..."

I went to Iceland and Germany.

Briley: "Yup, we're going to Colombia soon. Uh, and it's a really chill channel. It's just like experiencing travel in a different way."

Yeah, it's pretty cool. It's not like a full-on trying to win YouTube kind of thing, but it's an experiment in immersive 3D audio with a GoPro on your head. It's really fun! Anyway, I think you'll dig it.

Briley: "If you have headphones on, just go check it out."

Yeah, put your headphones on, check it out. It's called The Sound Traveler. I'll leave the link in the video description. I would love to get that over a hundred thousand subscribers. It's something I really love.

Ok, that's it for this episode of Smarter Every Day. I hope you enjoyed it. You may know that Audible's been sponsoring Smarter Every Day for a really long time. I love it. I love to use my ears to get smarter, and I do that with Audible. If you want to check out a free trial, go to audible.com/smarter.

We've recently started introducing Audible books to my children who loved it. Here's a hack for you. If you want to get like five books for the price of one, then get something called the Enchanted Collection or the Adventure Collection. It's 40 hours of audiobooks like White Fang, Gulliver's Travels, all kinds of cool stuff. Get the Enchanted Collection or the Adventure Collection at audible.com/smarter.

That's it. I'll leave links to everything in the video description. I hope this video earned your subscription. If not, no big deal. I hope from now on if you hear a sound, you think about where it's coming from, why you know it's coming from that position, whether it's temporal cues or spectral cues.

And I also hope every time you see a dog do this, you know that he's cheating. He's trying to use temporal cues instead of spectral cues, which is pretty doggone cool.

Anyway, I'm Destin, you're getting smarter every day. Have a good one. Don't cheat. It's important that you don't cheat. We need the data, okay?

"And you shot it, didn't you?"

Briley: "I did. I didn't mean to. I meant to shoot the branch."

I think that's why it came down though.

Briley: "It'll still be good."

You realize we used all of our country superpowers to do that?

Briley: "Pulled out every single stop that we had."

Briley: "Let's zero in this—let's zero in this scope with those cans."

Hey man, we did! We zeroed the scope with old cans. And then we got...