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Hey, you heard me, yeah, you come see our clubhouse and our tree.

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We are kids on a mission to educate ourselves about the NASA vision.

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Come explore math and science, cause that's what makes our alliance.

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We are the WAPA club, we yearn to learn and want to see.

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Everything that we can be, so come join us on our journey.

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Don't you touch that dial, and welcome to the NASA WAPA house.

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Wait, what are you doing?

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Look, you just poured orange juice in your cereal.

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I can't believe I just did this, and I'm so tired.

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Hi, Jacob.

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Hi.

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Oh, wow, this is so cool.

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Oh, this is my friend PJ, he's a friend from school.

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I taught him about our tree house.

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Hi.

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Hey.

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What are you guys doing in this place?

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You'll find out soon enough.

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I asked my two friends to join us.

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This is Kaylee and Catherine.

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Hi.

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Pretty neat.

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I like the slang.

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You all won't believe what I just did.

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What did you do?

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I was so tired that I accidentally poured orange juice in my cereal.

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My dog Rocky woke me up during the night.

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Sometime around 1030.

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So did my dog Arf.

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He just started barking for some reason.

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You have a dog named Arf?

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Well, yeah, it makes sense.

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You know, Arf, Arf.

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Arf, Arf, Arf.

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How long has this been going on?

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For the last several nights.

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Hey, KSNN is coming on.

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Oh, cool.

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And now, KSNN afternoon news.

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Brought to you by the Gumsonic Turbo Electric Toothbrush.

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Brush your teeth at supersonic speed with a Gumsonic Turbo.

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Good afternoon.

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I'm Ted Toombs.

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Today's top story, barking dogs are keeping our city's residents awake.

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Reports began to come in between 10 p.m. and midnight last night.

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Our on-the-scene reporter, I Am Listening, is live with this report.

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Thanks, Ted.

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As you well know, dogs will bark at just about anything.

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And they were certainly barking last night.

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But no one here seems to know exactly why.

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Some residents speculated that a cat or a prowler may have caused the dogs to bark.

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Or it could have been something as simple as the wind.

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We may never know.

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I Am Listening, KSNN news on the scene.

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Thanks, I Am, for that live report.

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Authorities are pleading with local residents to bring their dogs in tonight

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so that everyone can get some sleep.

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I'm Ted Toombs, and that's all the news.

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Wow, it's not just Rocky and Arf.

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Dogs are barking in other areas of our neighborhood.

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But what could be setting them off?

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It could be a sneaky cat just trying to tease them.

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Maybe the dogs are just talking to each other.

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Right, at that hour?

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I know we need to solve this problem.

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Remember, we have that big test coming up next week?

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I need my sleep. I can't afford another bad dream.

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Today's Monday. Hopefully we can figure this one out by test time.

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Maybe I can help you. I'm pretty good on the computer.

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We could do a little research on the Internet.

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Good idea.

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I think we can help, too.

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You know, six heads are better than one.

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I can't believe I didn't make the connection.

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You three are on KSNN. They called you the Treehouse Detectives.

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That's us.

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Maybe we could become Treehouse Detectives, too.

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Hmm, maybe if we had a team of Treehouse Detectives,

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we could figure out the problem of the barking dogs a lot faster.

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My mom works on the team at National Lightning Research Center.

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She says that they have a lot of success solving problems.

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Maybe a team approach is the way to go. Let's go for it.

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Okay. Let's get started.

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We don't know much.

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So far, all we know is that the dogs are barking and keeping everyone up.

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We need help. Let's go ask our neighbor, Dr. D.

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He helped us with the sink problem.

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I have an idea.

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Anytime we take a field trip, let's put it on the message board.

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That way, all of us will know what's going on.

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And any information you receive, just enter it into your computer.

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Good idea. Maybe just the three of us should go before school.

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I'll go to school early.

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We will, too.

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Let's go see Dr. D.

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Okay. I'm sure he's working on one of his projects.

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Hey, Dr. D.

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I think he can hear you. You're so loud.

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Hi, guys. What brings you over?

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You look a little tired.

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Some of us are very tired. We didn't get any sleep.

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Both of our dogs were barking last night.

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Dr. D., did Bernie bark last night?

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Now you know Bernie. He's a little old.

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It's time he's really out of it.

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Did Bernie ever bark?

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Oh, yeah. Sure.

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Especially when he would smell or hear something he wasn't familiar with.

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He'd start barking to scare it off.

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So could there be a strange smell in the air that's making all of the dogs in the neighborhood start barking?

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Could be.

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I thought the three of us would be back working on another problem.

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So I made up this board.

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Oh, the scientific method.

115
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I'll let you in on a little something.

116
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The scientific method really helps you to solve problems.

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Well, it helped us with the sink problem.

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Remember, the scientific method is a step-by-step way to solve problems.

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You can use it every day.

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Oh, it's all coming back to me now.

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I have something fun to show you that will help us review the scientific method.

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Let's go to my lab and try it out.

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Okay.

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Does anyone know what this device is called?

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I've seen one before, but I don't know what it's called.

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Well, it's called a Newton's cradle.

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If you wanted to find out how it worked, what would you do?

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I guess I'd play around with it.

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If we were following the scientific method,

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then the first thing we would do is to identify the problem.

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And, of course, we'd have to observe it.

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Well, you're observing it already by playing with it.

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What do you think we can say is the problem?

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Well, I noticed that when I pull this ball back and then release it,

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another ball pops out.

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Does that happen every time?

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And what about two balls?

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That's the problem.

139
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Remember, a problem has to be stated in the form of a question.

140
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So our problem is, what happens to the balls on the other side

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when I pull back a certain number of balls?

142
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Isn't the next part of the scientific method research?

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Yeah, that's correct.

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Oh, I like this kind of research.

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Let's see what happens when I pull back two balls.

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I'll collect data.

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Whoa, wait a minute.

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Don't forget, we have to control the variables.

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All the variables are the same except for one.

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So pull back your two balls the same distance that Jacob pulled back his one.

151
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That's right. I forgot about those variables.

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Wait, what happens if I do three balls?

153
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Are we ready for our hypothesis yet?

154
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I know the hypothesis.

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When you let go of two balls, two balls come out.

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And if you let go of three balls, three balls come out.

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That's right.

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Remember, the hypothesis has to be written so it can be tested.

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For example, the same number of balls I pull back will come out on the other side.

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Okay, are we ready to experiment yet?

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That's my favorite part.

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Okay, let's test the hypothesis.

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Let's see what happens.

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If I pull back four balls, then four balls should come out on the other side.

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Wow, our hypothesis was correct.

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Congratulations.

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But remember, the data does not support the hypothesis.

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You have to try again.

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But how do we observe for our problem of the barking dogs?

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We can't stay up all night waiting for the dogs to start barking.

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Well, we could.

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Could?

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Not me.

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Remember, I have that big test next week.

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I think we need to go back to the tree house to talk about this problem.

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And then we need to decide what we want to research.

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Thanks for all your help, Dr. Dean.

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See you, Dr. Dean.

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Bye-bye, guys.

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Let's see. Remember our need-to-know board?

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How could I forget that one?

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Hey, it did help us solve the stink problem.

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Okay, what do we know?

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We know that dogs are barking at all hours of the night.

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And we know that it's happening in our neighborhood.

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We need to know what's making them bark.

187
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Hmm, what would make a dog bark?

188
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It could be a prowler or a robber staking out the area.

189
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Or it could be just a mad cat getting evil.

190
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Yeah, but if it was a prowler, wouldn't KSNN report about it?

191
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Hmm, that's true.

192
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And I haven't heard anything about prowlers or robbers on KSNN.

193
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Cats aren't a new problem, but whatever's setting off the barking definitely is.

194
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Well, remember what Dr. Dean told us about Bernie.

195
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Bernie barks at strange smells or sounds.

196
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KSNN didn't report any environmental problems with the smell.

197
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Since Dr. Dean said it could also be sound, then let's investigate sound.

198
00:08:32,000 --> 00:08:35,000
But remember the stink. It could be anything.

199
00:08:35,000 --> 00:08:38,000
Yes, we need to find out a little more about sound.

200
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We need to start our sound research.

201
00:08:40,000 --> 00:08:42,000
We should also check out the NASA White Falls website.

202
00:08:42,000 --> 00:08:44,000
I saw something about it on sound.

203
00:08:44,000 --> 00:08:47,000
You will love the NASA White Falls website.

204
00:08:47,000 --> 00:08:51,000
My mom's friend Ms. Leslie Bui works over at the Children's Museum.

205
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Maybe she can help us with the sound problem.

206
00:08:53,000 --> 00:08:55,000
I can't go over there right now.

207
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I can't go either.

208
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Okay, I'll put it in the computer.

209
00:08:58,000 --> 00:09:00,000
Maybe one of the other treehouse detectives will show up.

210
00:09:09,000 --> 00:09:11,000
This place is really neat.

211
00:09:11,000 --> 00:09:14,000
Yeah, but I think we need to find Ms. Leslie Bui.

212
00:09:14,000 --> 00:09:17,000
Hi, I'm Leslie Bui. I'm curator here at the Children's Museum of Virginia.

213
00:09:17,000 --> 00:09:19,000
How can I help you?

214
00:09:19,000 --> 00:09:23,000
Hi, some of our dogs are barking and are waking us up at night.

215
00:09:23,000 --> 00:09:27,000
And we think that a really strange sound may be making them bark.

216
00:09:27,000 --> 00:09:29,000
Can you tell us what sound is?

217
00:09:29,000 --> 00:09:32,000
I think I can help you understand. Come over this way.

218
00:09:36,000 --> 00:09:38,000
Sound is created by vibration.

219
00:09:38,000 --> 00:09:42,000
A vibration is a back and forth motion a lot like this slinky.

220
00:09:45,000 --> 00:09:48,000
An object vibrates and pushes air molecules around.

221
00:09:48,000 --> 00:09:51,000
Then these set other air molecules into motion.

222
00:09:51,000 --> 00:09:54,000
But we can't actually see the sound waves.

223
00:09:54,000 --> 00:09:56,000
But I can help you see the vibrations.

224
00:09:56,000 --> 00:09:58,000
This is a tuning fork. Listen.

225
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I can hear a sound.

226
00:10:02,000 --> 00:10:03,000
Me too.

227
00:10:03,000 --> 00:10:06,000
And I can help you see the vibrations.

228
00:10:07,000 --> 00:10:09,000
Vibration

229
00:10:17,000 --> 00:10:19,000
What is frequency?

230
00:10:19,000 --> 00:10:21,000
Frequency is the rate of vibration.

231
00:10:21,000 --> 00:10:24,000
The higher the frequency, the higher the pitch.

232
00:10:24,000 --> 00:10:26,000
Here, let me show you.

233
00:10:26,000 --> 00:10:29,000
I've flattened a straw and cut points.

234
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Now blow hard.

235
00:10:32,000 --> 00:10:34,000
I'll cut the straw.

236
00:10:38,000 --> 00:10:39,000
What do you notice?

237
00:10:39,000 --> 00:10:41,000
It's higher.

238
00:10:41,000 --> 00:10:43,000
I'll cut it again.

239
00:10:43,000 --> 00:10:45,000
What changes?

240
00:10:46,000 --> 00:10:48,000
It's even higher.

241
00:10:48,000 --> 00:10:50,000
It's kind of like these tubes.

242
00:10:50,000 --> 00:10:53,000
The longer the tube, the lower the sound.

243
00:10:56,000 --> 00:10:59,000
That's right. The shorter the tube, the higher the pitch.

244
00:10:59,000 --> 00:11:02,000
The shorter the tube, the higher the sound.

245
00:11:02,000 --> 00:11:04,000
It's a lot like this straw.

246
00:11:05,000 --> 00:11:07,000
Bianca, can you hear me?

247
00:11:07,000 --> 00:11:10,000
Yes, Kaylee. We're having so much fun.

248
00:11:10,000 --> 00:11:12,000
But now it's time to go.

249
00:11:12,000 --> 00:11:14,000
I don't want to go.

250
00:11:14,000 --> 00:11:17,000
But I'll go tell Mrs. Bowie thanks for the information.

251
00:11:17,000 --> 00:11:19,000
Okay. See ya.

252
00:11:19,000 --> 00:11:20,000
Bye.

253
00:11:20,000 --> 00:11:21,000
Bye-bye.

254
00:11:24,000 --> 00:11:25,000
Let's get back to work.

255
00:11:25,000 --> 00:11:28,000
When my dog starts barking, I'm usually asleep.

256
00:11:28,000 --> 00:11:31,000
Maybe we can ask other people to observe their dogs at night.

257
00:11:31,000 --> 00:11:34,000
I'll call Kassadin and ask him to announce it on the news.

258
00:11:34,000 --> 00:11:37,000
A big part of the scientific method is observation.

259
00:11:37,000 --> 00:11:39,000
Remember what Dr. D said?

260
00:11:39,000 --> 00:11:41,000
You have to define the problem through observation.

261
00:11:41,000 --> 00:11:44,000
Observation is my favorite part of the scientific method.

262
00:11:44,000 --> 00:11:46,000
If you want to learn more about the scientific method,

263
00:11:46,000 --> 00:11:48,000
you should go to the NASA Wi-Fi's website.

264
00:11:50,000 --> 00:11:51,000
Kassadin is great.

265
00:11:51,000 --> 00:11:54,000
Look, we're already getting responses from different neighborhoods.

266
00:11:54,000 --> 00:11:55,000
Let's see.

267
00:11:55,000 --> 00:11:57,000
This person from Cochlea, Cascade,

268
00:11:57,000 --> 00:12:00,000
says her dogs are barking early in the morning and late at night.

269
00:12:00,000 --> 00:12:04,000
But in Midnight Growl, they say that they have barking mainly in the morning.

270
00:12:04,000 --> 00:12:07,000
Let's email them back and see if they notice any funny smells,

271
00:12:07,000 --> 00:12:10,000
sounds, or creatures around the house when the dogs were barking.

272
00:12:10,000 --> 00:12:12,000
How are we going to sort all this data?

273
00:12:12,000 --> 00:12:15,000
Data collection is also a big part of the scientific method.

274
00:12:15,000 --> 00:12:18,000
With this data, we might be able to get to the bottom of this.

275
00:12:18,000 --> 00:12:21,000
My mom told me about someone at NASA Langley

276
00:12:21,000 --> 00:12:24,000
who spends a lot of time collecting and analyzing data.

277
00:12:24,000 --> 00:12:26,000
Maybe we should talk to the experts at NASA.

278
00:12:26,000 --> 00:12:30,000
Computer, get me an expert at NASA on analyzing and collecting data.

279
00:12:33,000 --> 00:12:36,000
Hi, I'm Dr. Kara Lotterello at the NASA Langley Research Center.

280
00:12:36,000 --> 00:12:39,000
Hi, we're trying to solve the problem of the barking dogs.

281
00:12:39,000 --> 00:12:41,000
I might be able to help you.

282
00:12:41,000 --> 00:12:42,000
We collect a lot of data here.

283
00:12:42,000 --> 00:12:45,000
That's how we understand problems so we can solve them.

284
00:12:45,000 --> 00:12:48,000
Right now, we're developing a flight simulation experiment

285
00:12:48,000 --> 00:12:50,000
so we can test a new display idea.

286
00:12:50,000 --> 00:12:53,000
We'll collect data from pilots to see if they can fly you

287
00:12:53,000 --> 00:12:55,000
and your family around more safely with our new display,

288
00:12:55,000 --> 00:12:57,000
as opposed to the old one.

289
00:12:57,000 --> 00:12:59,000
We've received a lot of emails from neighborhoods.

290
00:12:59,000 --> 00:13:02,000
We really need to know the best way to keep track of all this data.

291
00:13:02,000 --> 00:13:04,000
How do you sort and collect your data?

292
00:13:04,000 --> 00:13:06,000
Well, first we start with a question

293
00:13:06,000 --> 00:13:08,000
or a statement of what we think is happening.

294
00:13:08,000 --> 00:13:10,000
We call that statement a hypothesis.

295
00:13:10,000 --> 00:13:12,000
So, for example, in my case,

296
00:13:12,000 --> 00:13:15,000
I hypothesize that the new display will be better than the old display

297
00:13:15,000 --> 00:13:18,000
and that that will be true for both younger and older pilots.

298
00:13:18,000 --> 00:13:20,000
The data we collect will fill in the test matrix.

299
00:13:20,000 --> 00:13:23,000
Each data point can be considered an observation.

300
00:13:23,000 --> 00:13:27,000
In my experiment, I'm using the computer and sensors in the computer

301
00:13:27,000 --> 00:13:29,000
to take these observations.

302
00:13:29,000 --> 00:13:32,000
You can also take direct observations by looking at things yourself

303
00:13:32,000 --> 00:13:36,000
or indirect observations by asking other people to report things to you.

304
00:13:36,000 --> 00:13:38,000
How do we know if data is important to our problem?

305
00:13:38,000 --> 00:13:41,000
Well, hopefully your data supports your hypothesis.

306
00:13:41,000 --> 00:13:43,000
That means that the conditions you thought were important

307
00:13:43,000 --> 00:13:45,000
actually did influence your measures.

308
00:13:45,000 --> 00:13:48,000
If it doesn't, then you might want to collect some more data,

309
00:13:48,000 --> 00:13:51,000
some different data, or rethink your hypothesis.

310
00:13:51,000 --> 00:13:55,000
This is great. Remember the matrix Dr. D showed us in the stink problem?

311
00:13:55,000 --> 00:13:59,000
We can use that to help us rule out some of the possible sources of the problem.

312
00:13:59,000 --> 00:14:01,000
But how do we set up a matrix?

313
00:14:01,000 --> 00:14:03,000
You really should set up your test matrix ahead of time,

314
00:14:03,000 --> 00:14:05,000
before you collect data.

315
00:14:05,000 --> 00:14:08,000
In my experiment, it's pretty simple, since I only have two factors of interest,

316
00:14:08,000 --> 00:14:11,000
the display type and the age of the pilots.

317
00:14:11,000 --> 00:14:13,000
And I have two levels for each of these factors.

318
00:14:13,000 --> 00:14:16,000
For the display type, I have a new display and an old display.

319
00:14:16,000 --> 00:14:19,000
And for the age of the pilots, I have younger and older pilots.

320
00:14:19,000 --> 00:14:21,000
Your matrix helps you organize your data,

321
00:14:21,000 --> 00:14:25,000
so you can look at it, analyze it, and understand what's important about your problem.

322
00:14:25,000 --> 00:14:28,000
We can look at the data and get an idea about the source.

323
00:14:28,000 --> 00:14:30,000
Thanks a lot for all your help.

324
00:14:30,000 --> 00:14:33,000
Now we might be able to actually make some sense of all this.

325
00:14:33,000 --> 00:14:35,000
Thanks for stopping by. Good luck.

326
00:14:35,000 --> 00:14:37,000
Wow, we have more emails.

327
00:14:37,000 --> 00:14:42,000
Maybe we will see a pattern in the increase of strange smells, sounds, or even prowlers.

328
00:14:42,000 --> 00:14:44,000
Look, this person from Cochlear Cascade

329
00:14:44,000 --> 00:14:47,000
says she didn't notice any strange smells when her dog started barking.

330
00:14:47,000 --> 00:14:49,000
Smells seems like such a stretch.

331
00:14:49,000 --> 00:14:52,000
I don't think we're going to solve this problem any time today.

332
00:14:52,000 --> 00:14:55,000
I agree. Tonight, try to see what's going on when your dog starts barking.

333
00:14:55,000 --> 00:14:59,000
I'll try. Let's all try. We need to figure this one out quick.

334
00:15:00,000 --> 00:15:03,000
So what's up? Will the dogs continue to bark?

335
00:15:03,000 --> 00:15:06,000
Are the treehouse detectives asking the right questions?

336
00:15:06,000 --> 00:15:09,000
Will the scientific method work to solve the problem?

337
00:15:09,000 --> 00:15:13,000
Tune in next time for The Case of the Barking Dogs.

338
00:15:15,000 --> 00:15:21,000
We can use our information to plot exactly where the dogs are barking and possible causes.

339
00:15:21,000 --> 00:15:24,000
Let's use black pushpins for dogs barking in the night,

340
00:15:24,000 --> 00:15:26,000
blue ones for dogs barking in the day,

341
00:15:26,000 --> 00:15:28,000
green for prowlers,

342
00:15:28,000 --> 00:15:30,000
yellow for loud sounds,

343
00:15:30,000 --> 00:15:32,000
and red ones for strange smells.

344
00:15:32,000 --> 00:15:34,000
We have too many emails but not enough pushpins.

345
00:15:34,000 --> 00:15:38,000
Remember in school, we used pictographs to represent large numbers.

346
00:15:38,000 --> 00:15:41,000
Yeah, each pushpin can equal five barking dogs.

347
00:15:41,000 --> 00:15:44,000
In Midnight Growl, we have 10 dogs barking in the day.

348
00:15:44,000 --> 00:15:47,000
So I'll put two blue pushpins.

349
00:15:48,000 --> 00:15:53,000
In Cochlear Cascade, we have 20 dogs barking in the day and 10 dogs barking at night.

350
00:15:53,000 --> 00:15:57,000
That means we have four blue pushpins and two black ones.

351
00:15:57,000 --> 00:16:01,000
Let's just put in a green pushpin for each neighborhood that reported prowlers.

352
00:16:01,000 --> 00:16:05,000
That would be Midnight Growl and Sleepless Subdivision.

353
00:16:05,000 --> 00:16:08,000
Hmm, if prowlers are the smallest,

354
00:16:09,000 --> 00:16:12,000
Hmm, if prowlers are the source of the problem,

355
00:16:12,000 --> 00:16:15,000
then wouldn't each neighborhood that reported barking dogs have prowlers?

356
00:16:15,000 --> 00:16:17,000
And those with prowlers would have barking.

357
00:16:17,000 --> 00:16:19,000
But by looking at the map, we can see this isn't true.

358
00:16:19,000 --> 00:16:21,000
So I guess prowlers aren't causing the problem.

359
00:16:21,000 --> 00:16:23,000
What about smells?

360
00:16:23,000 --> 00:16:25,000
So far, no one has reported any bad smells.

361
00:16:25,000 --> 00:16:29,000
And if it was a bad smell, wouldn't KSNN say something about it?

362
00:16:29,000 --> 00:16:31,000
Good point. What about sound?

363
00:16:31,000 --> 00:16:36,000
In Midnight Growl, we have dogs barking and some residents are noticing loud noises.

364
00:16:36,000 --> 00:16:39,000
I'll put a yellow pushpin in Midnight Growl.

365
00:16:39,000 --> 00:16:44,000
In Cochlear Cascade, there are dogs barking and they notice loud sounds.

366
00:16:44,000 --> 00:16:46,000
Another pushpin for that neighborhood.

367
00:16:46,000 --> 00:16:48,000
This looks promising.

368
00:16:48,000 --> 00:16:51,000
In the email from Sound and Seaside, they've noticed loud sounds.

369
00:16:51,000 --> 00:16:53,000
Let me get this one.

370
00:16:53,000 --> 00:16:55,000
But there are no dogs barking.

371
00:16:55,000 --> 00:16:58,000
So does this mean there's no connection to sound?

372
00:16:58,000 --> 00:16:59,000
My guess is no.

373
00:16:59,000 --> 00:17:02,000
We might want to research sound a lot more

374
00:17:02,000 --> 00:17:07,000
because both Midnight Growl and Cochlear Cascade have barking dogs and sound.

375
00:17:07,000 --> 00:17:09,000
There may be a connection.

376
00:17:09,000 --> 00:17:12,000
You would think that all dogs would start barking at all loud sounds.

377
00:17:12,000 --> 00:17:14,000
I think so far it's sound.

378
00:17:14,000 --> 00:17:16,000
The map really helps us see it.

379
00:17:16,000 --> 00:17:18,000
It sure has helped us to solve the problem.

380
00:17:18,000 --> 00:17:23,000
You know, at the NASA White Falls website, there are some great activities using a map and a matrix.

381
00:17:23,000 --> 00:17:24,000
You should check it out.

382
00:17:24,000 --> 00:17:26,000
I think we need to concentrate on sound a little more.

383
00:17:26,000 --> 00:17:28,000
Let's go back to our neat snowboard.

384
00:17:33,000 --> 00:17:35,000
We know dogs are barking.

385
00:17:35,000 --> 00:17:39,000
And we know that vibrations produce sound and that sound travels in waves.

386
00:17:39,000 --> 00:17:44,000
We need to know more about how sound travels and how we hear it.

387
00:17:44,000 --> 00:17:47,000
Let's think about sounds that make dogs bark.

388
00:17:47,000 --> 00:17:48,000
Garbage trucks.

389
00:17:48,000 --> 00:17:49,000
Sirens.

390
00:17:49,000 --> 00:17:50,000
Stephenoids.

391
00:17:50,000 --> 00:17:51,000
And work trucks.

392
00:17:51,000 --> 00:17:55,000
I wonder if there's a reason why the dogs aren't hearing the sound in Sound and Seaside.

393
00:17:55,000 --> 00:17:56,000
Maybe they have wax in their ears.

394
00:17:56,000 --> 00:17:58,000
Yeah, right.

395
00:17:58,000 --> 00:18:00,000
Maybe something's blocking the sound.

396
00:18:00,000 --> 00:18:02,000
Maybe a wall keeping it from going to other parts of the sound.

397
00:18:02,000 --> 00:18:03,000
That's a good idea.

398
00:18:03,000 --> 00:18:05,000
Like what?

399
00:18:05,000 --> 00:18:06,000
Maybe a wall.

400
00:18:06,000 --> 00:18:08,000
Maybe more dogs are kept inside in that neighborhood.

401
00:18:08,000 --> 00:18:10,000
That could be it.

402
00:18:10,000 --> 00:18:16,000
I think there's more connections between barking dogs and sound than there is with prowlers or even smells.

403
00:18:16,000 --> 00:18:18,000
I say we concentrate on sound.

404
00:18:18,000 --> 00:18:20,000
My mom's friend knows a lot about ears.

405
00:18:20,000 --> 00:18:22,000
I think she's called an audiologist.

406
00:18:22,000 --> 00:18:24,000
Can you go visit her?

407
00:18:24,000 --> 00:18:26,000
I can't. I have to do my homework.

408
00:18:26,000 --> 00:18:27,000
Jacob and I will go.

409
00:18:27,000 --> 00:18:29,000
Her name is Ms. Helen Denny.

410
00:18:29,000 --> 00:18:31,000
She works at Sentara Hampton General Hospital.

411
00:18:31,000 --> 00:18:33,000
She says we can come over anytime.

412
00:18:33,000 --> 00:18:35,000
I'll email our parents and tell them where we're going.

413
00:18:35,000 --> 00:18:36,000
Great. Let's get up and go.

414
00:18:36,000 --> 00:18:37,000
Okay.

415
00:18:43,000 --> 00:18:45,000
We're known as the Treehouse Detectives.

416
00:18:45,000 --> 00:18:46,000
Oh.

417
00:18:46,000 --> 00:18:48,000
We're trying to get some sleep, but the neighborhood dogs are keeping us up.

418
00:18:48,000 --> 00:18:49,000
Who knew?

419
00:18:49,000 --> 00:18:51,000
We wanted to know how our ears work.

420
00:18:51,000 --> 00:18:53,000
That way we can figure out why the dogs keep barking.

421
00:18:53,000 --> 00:18:55,000
And how sound travels.

422
00:18:55,000 --> 00:18:57,000
If we know how sound travels, that might help us solve the problem.

423
00:18:57,000 --> 00:18:59,000
I think I can help you out.

424
00:18:59,000 --> 00:19:00,000
Let's move into the other room.

425
00:19:00,000 --> 00:19:01,000
Cool.

426
00:19:02,000 --> 00:19:03,000
What is all this stuff?

427
00:19:03,000 --> 00:19:05,000
This is equipment we use to test people's hearing.

428
00:19:05,000 --> 00:19:07,000
Can you tell us how our ears work?

429
00:19:07,000 --> 00:19:08,000
Sure.

430
00:19:08,000 --> 00:19:10,000
The outer ear collects and concentrates the sound energy.

431
00:19:10,000 --> 00:19:14,000
Then this is channeled down the ear canal, and the eardrum vibrates,

432
00:19:14,000 --> 00:19:16,000
and so do the small bones within the ear.

433
00:19:16,000 --> 00:19:20,000
Then the sounds go through the cochlea, the hair cells bend,

434
00:19:20,000 --> 00:19:23,000
and then the impulses are sent up the auditory nerve into the brain,

435
00:19:23,000 --> 00:19:24,000
where they're decoded.

436
00:19:24,000 --> 00:19:26,000
Other sounds people can't hear?

437
00:19:26,000 --> 00:19:28,000
Sure, if they're above a certain frequency.

438
00:19:28,000 --> 00:19:33,000
The human ear can hear frequencies between 20 and 20,000 vibrations a second.

439
00:19:33,000 --> 00:19:34,000
Frequencies.

440
00:19:34,000 --> 00:19:36,000
Hmm, that might be a clue.

441
00:19:36,000 --> 00:19:37,000
Thanks for all your help.

442
00:19:37,000 --> 00:19:38,000
Sure.

443
00:19:38,000 --> 00:19:39,000
Bye.

444
00:19:39,000 --> 00:19:40,000
Bye, and good luck.

445
00:19:40,000 --> 00:19:41,000
Thanks.

446
00:19:42,000 --> 00:19:44,000
I bet NASA Langley Research Center could help us.

447
00:19:44,000 --> 00:19:47,000
My neighbor researches noise pollution and how it affects us.

448
00:19:47,000 --> 00:19:49,000
I've heard of air pollution, but noise pollution?

449
00:19:49,000 --> 00:19:50,000
Yes.

450
00:19:50,000 --> 00:19:52,000
Her name is Ms. Brenda Sullivan.

451
00:19:52,000 --> 00:19:54,000
Let's go over and talk to her.

452
00:19:54,000 --> 00:19:56,000
Okay, I'll call my mom for a ride.

453
00:19:56,000 --> 00:19:59,000
I'm sure glad it's a half day so we can get all this research done.

454
00:19:59,000 --> 00:20:00,000
Yeah.

455
00:20:01,000 --> 00:20:03,000
Too bad PJ couldn't make it.

456
00:20:04,000 --> 00:20:06,000
What or who is that?

457
00:20:06,000 --> 00:20:07,000
Oh, that's Fred DeHank.

458
00:20:07,000 --> 00:20:09,000
You must be the treehouse detectives.

459
00:20:09,000 --> 00:20:11,000
I'm Bianca, and this is Jacob.

460
00:20:11,000 --> 00:20:13,000
We're trying to solve a really big problem.

461
00:20:13,000 --> 00:20:17,000
Dogs are barking and keeping us up at night and in the early morning.

462
00:20:17,000 --> 00:20:18,000
I heard about that in the news.

463
00:20:18,000 --> 00:20:22,000
We think that a really loud sound might be making them bark.

464
00:20:22,000 --> 00:20:23,000
We're researching sound.

465
00:20:23,000 --> 00:20:26,000
We'd like to learn how you deal with sound problems.

466
00:20:26,000 --> 00:20:30,000
Well, I'm a psychoacoustician here at NASA Langley Research Center.

467
00:20:30,000 --> 00:20:31,000
That's a really big word.

468
00:20:31,000 --> 00:20:33,000
I don't think I can even say that.

469
00:20:33,000 --> 00:20:35,000
So what do you do here?

470
00:20:35,000 --> 00:20:39,000
Well, as a psychoacoustician, I design, conduct, and analyze tests

471
00:20:39,000 --> 00:20:43,000
that investigate the psychological effects of noise on people.

472
00:20:43,000 --> 00:20:45,000
Let me show you one of my labs.

473
00:20:46,000 --> 00:20:47,000
Is this a real plane?

474
00:20:47,000 --> 00:20:49,000
No, this is a fake.

475
00:20:49,000 --> 00:20:51,000
But we go up in real planes, we make recordings,

476
00:20:51,000 --> 00:20:54,000
we bring them down to the lab, and we modify them.

477
00:20:54,000 --> 00:20:56,000
Then we can play them back to people in here

478
00:20:56,000 --> 00:20:58,000
and find out which kind of sounds they prefer.

479
00:20:58,000 --> 00:21:00,000
So what kind of sounds do people prefer?

480
00:21:00,000 --> 00:21:02,000
Well, quiet ones, really.

481
00:21:02,000 --> 00:21:07,000
We hear from 20 vibrations per second to 20,000 vibrations per second,

482
00:21:07,000 --> 00:21:11,000
and the low-frequency ones bother us less than the high frequencies.

483
00:21:11,000 --> 00:21:15,000
For instance, have you heard a piece of chalk scratching on a chalkboard?

484
00:21:15,000 --> 00:21:16,000
Yuck.

485
00:21:16,000 --> 00:21:17,000
Well, that's a high-frequency sound.

486
00:21:17,000 --> 00:21:20,000
What about dogs? Do they hear differently from us?

487
00:21:20,000 --> 00:21:22,000
Well, I'm not an expert on dogs,

488
00:21:22,000 --> 00:21:24,000
but I know dogs can hear higher frequencies than we do.

489
00:21:24,000 --> 00:21:26,000
They can hear very high frequencies.

490
00:21:26,000 --> 00:21:27,000
Come on, let's go.

491
00:21:31,000 --> 00:21:36,000
So, we need to find out what kind of things make very high-frequency noises.

492
00:21:36,000 --> 00:21:38,000
What about machines or factories?

493
00:21:38,000 --> 00:21:39,000
They both might be possibilities.

494
00:21:39,000 --> 00:21:42,000
That could be it. It could be a noise from a nearby factory.

495
00:21:42,000 --> 00:21:44,000
We might have the answer.

496
00:21:44,000 --> 00:21:46,000
You mean the hypothesis.

497
00:21:46,000 --> 00:21:48,000
You need to go and talk to my friend, the veterinarian.

498
00:21:48,000 --> 00:21:50,000
His name's Dr. Gooding.

499
00:21:50,000 --> 00:21:52,000
Oh, here he is. He's right around the corner.

500
00:21:52,000 --> 00:21:55,000
Great. I love going to pet hospitals.

501
00:21:55,000 --> 00:21:57,000
I'll call my parents and see if it's okay.

502
00:21:58,000 --> 00:22:00,000
I wonder what kind of neat pets we will see today.

503
00:22:00,000 --> 00:22:03,000
Hi, we're the Treehouse Detectives. We're here to see Dr. Gooding.

504
00:22:03,000 --> 00:22:05,000
Please come this way. How can I help you?

505
00:22:11,000 --> 00:22:12,000
Thanks for helping us.

506
00:22:12,000 --> 00:22:14,000
I'm Jacob, and this is Bianca.

507
00:22:14,000 --> 00:22:17,000
Have you heard about the dog barking problem on KSNN?

508
00:22:17,000 --> 00:22:18,000
Yes, I have.

509
00:22:18,000 --> 00:22:20,000
I know it's keeping a lot of people up at night.

510
00:22:20,000 --> 00:22:22,000
Tell me about it.

511
00:22:22,000 --> 00:22:25,000
We need to know dogs hear sounds differently from us.

512
00:22:26,000 --> 00:22:28,000
Whoa! Look at that big dog.

513
00:22:28,000 --> 00:22:30,000
I know he can hear us.

514
00:22:31,000 --> 00:22:35,000
Yes, dogs tend to hear at a much higher frequency than human beings.

515
00:22:35,000 --> 00:22:39,000
This means they can hear sounds that the human ear cannot hear.

516
00:22:39,000 --> 00:22:43,000
Dogs can hear sounds between 67 Hz and 45 kHz.

517
00:22:43,000 --> 00:22:47,000
Now, people can only hear between 20 Hz and 20 kHz.

518
00:22:48,000 --> 00:22:50,000
Do the insides of dogs' ears look like ours?

519
00:22:50,000 --> 00:22:51,000
What?

520
00:22:51,000 --> 00:22:53,000
That's actually a good question.

521
00:22:53,000 --> 00:22:56,000
I have something to show you. Let's go, guys.

522
00:22:59,000 --> 00:23:01,000
Let's take a look at Millie's ears.

523
00:23:02,000 --> 00:23:06,000
Actually, the anatomy of the human ear is similar to that of the dog.

524
00:23:06,000 --> 00:23:09,000
Those are actual pictures of Millie's ears.

525
00:23:10,000 --> 00:23:14,000
However, dogs have some equipment or parts that might have better hearing.

526
00:23:14,000 --> 00:23:22,000
For example, dogs tend to have a long ear canal that might allow sound to be funneled or directed into the hearing apparatus.

527
00:23:22,000 --> 00:23:30,000
It's a lot like this funnel, something that is used to direct water into this bottle so that you don't spill it.

528
00:23:31,000 --> 00:23:35,000
So, that's why dogs can hear noises at higher frequencies.

529
00:23:35,000 --> 00:23:37,000
They can hear things that we can't.

530
00:23:38,000 --> 00:23:42,000
That's true. Dogs used to be wild before they were domesticated.

531
00:23:42,000 --> 00:23:46,000
They had to survive by finding food and escaping predators.

532
00:23:46,000 --> 00:23:50,000
Therefore, they might have had to depend on their ears to survive.

533
00:23:50,000 --> 00:23:51,000
That's cool.

534
00:23:51,000 --> 00:23:55,000
Dr. Gooding, do you know any good examples of dogs that can hear?

535
00:23:55,000 --> 00:23:56,000
Hmm, let's see.

536
00:23:56,000 --> 00:24:00,000
Are you familiar with dog whistles or pest zappers?

537
00:24:00,000 --> 00:24:03,000
These are good examples of high-frequency sounds.

538
00:24:03,000 --> 00:24:05,000
Thanks, doctor, for all your information.

539
00:24:05,000 --> 00:24:06,000
We'll see you later.

540
00:24:06,000 --> 00:24:07,000
Goodbye.

541
00:24:07,000 --> 00:24:08,000
Bye.

542
00:24:09,000 --> 00:24:12,000
I wonder if more people have bought dog whistles lately.

543
00:24:12,000 --> 00:24:13,000
We should check that out.

544
00:24:13,000 --> 00:24:18,000
Hey, guys, there's a cool activity at the NASA Wi-Fi's website where it lets you build your own dog whistle.

545
00:24:18,000 --> 00:24:20,000
It's called Dog Whistle.

546
00:24:20,000 --> 00:24:21,000
We should check that out.

547
00:24:21,000 --> 00:24:27,000
Hey, guys, there's a cool activity at the NASA Wi-Fi's website where it lets you build a sound cone and gives you superhuman hearing.

548
00:24:27,000 --> 00:24:28,000
You should check it out.

549
00:24:32,000 --> 00:24:36,000
We interrupt this broadcast for a special Kid Science News Network bulletin.

550
00:24:36,000 --> 00:24:39,000
We go now live to reporter I Am Listening.

551
00:24:39,000 --> 00:24:44,000
Thanks, Ted. There's nothing new to report on the barking dog dilemma.

552
00:24:44,000 --> 00:24:46,000
The mystery has not been solved.

553
00:24:47,000 --> 00:24:51,000
I repeat, the mystery has not been solved.

554
00:24:51,000 --> 00:25:00,000
Many people continue to suffer from lack of sleep as the dogs continue to bark between 10 p.m. and midnight every night.

555
00:25:00,000 --> 00:25:03,000
I'm I Am Listening, KSNN News.

556
00:25:03,000 --> 00:25:05,000
Back to you, Ted.

557
00:25:05,000 --> 00:25:08,000
Thanks for that informative report, I Am.

558
00:25:08,000 --> 00:25:14,000
What? This just in, Gumsonic, manufacturer of the most popular electric toothbrushes on the market,

559
00:25:14,000 --> 00:25:19,000
announced today that there may be problems with their newest model, the Gumsonic Turbo.

560
00:25:19,000 --> 00:25:25,000
Gumsonic stressed that there is no threat to the general population and more studies are being conducted.

561
00:25:25,000 --> 00:25:27,000
More after this.

562
00:25:27,000 --> 00:25:33,000
We need to learn more about very high frequency sounds because that is what the veterinarians said dogs can hear and we can't.

563
00:25:33,000 --> 00:25:37,000
So we need to find out what kinds of things make high frequency noises.

564
00:25:37,000 --> 00:25:44,000
Hmm, Ms. Sullivan says it could be the factory and Dr. Gooding says it could be pest zappers or dog whistles.

565
00:25:44,000 --> 00:25:46,000
I think they're all possibilities.

566
00:25:46,000 --> 00:25:49,000
I think the factory is it. Yes, we might have the answer.

567
00:25:49,000 --> 00:25:51,000
You mean a hypothesis.

568
00:25:51,000 --> 00:25:57,000
Before we jump to any conclusions, we need to learn more about how sound travels because I don't know if sound can travel that far.

569
00:25:57,000 --> 00:26:00,000
Look, we have an email from Dr. D.

570
00:26:00,000 --> 00:26:03,000
He wants to take us to NASA. He's going to meet us outside.

571
00:26:04,000 --> 00:26:07,000
I talked to Brenda Sullivan. She's allowing us to use the anechoic chamber.

572
00:26:07,000 --> 00:26:09,000
The what? Just follow me.

573
00:26:12,000 --> 00:26:14,000
What do you think of this?

574
00:26:14,000 --> 00:26:16,000
Wow, this is pretty amazing.

575
00:26:16,000 --> 00:26:19,000
An anechoic chamber is a special chamber that absorbs sounds.

576
00:26:19,000 --> 00:26:22,000
Sounds can't bounce off the walls, the ceiling or the floor.

577
00:26:22,000 --> 00:26:25,000
This is weird. What are all those things on the wall?

578
00:26:25,000 --> 00:26:28,000
They're wedge-shaped sponges. That's what absorbs the sound.

579
00:26:28,000 --> 00:26:30,000
Let's try an experiment.

580
00:26:30,000 --> 00:26:33,000
Bianca, stand over here. Matthew, go across the room from her.

581
00:26:33,000 --> 00:26:34,000
Okay.

582
00:26:34,000 --> 00:26:38,000
Now face into the wall, Bianca, and yell as loud as you can. Go ahead.

583
00:26:38,000 --> 00:26:40,000
Wow!

584
00:26:40,000 --> 00:26:41,000
What did you hear?

585
00:26:41,000 --> 00:26:43,000
I could hear, but she wasn't that loud.

586
00:26:43,000 --> 00:26:46,000
I yelled as loud as I could, and you still couldn't hear me?

587
00:26:46,000 --> 00:26:50,000
Not really, and that's unusual for once.

588
00:26:51,000 --> 00:26:53,000
Let me show you another property of sound.

589
00:26:53,000 --> 00:26:57,000
Now, Matthew, stand about a half a meter away from the speaker.

590
00:26:57,000 --> 00:26:59,000
Now, after I turn up the sound really loud,

591
00:26:59,000 --> 00:27:03,000
I want you to walk backwards until the sound appears to be about half as loud.

592
00:27:03,000 --> 00:27:04,000
Okay.

593
00:27:04,000 --> 00:27:05,000
Ready?

594
00:27:10,000 --> 00:27:12,000
It sounds about half as loud here.

595
00:27:12,000 --> 00:27:16,000
It's not surprising to find out that sound gets softer as you move further away from the source.

596
00:27:16,000 --> 00:27:18,000
This is called an inverse relation.

597
00:27:18,000 --> 00:27:21,000
Mathematics will help us understand how it works.

598
00:27:21,000 --> 00:27:25,000
Every time you move a little more than three times further away,

599
00:27:25,000 --> 00:27:27,000
it will sound half as loud.

600
00:27:28,000 --> 00:27:31,000
I have so much information in my head, it hurts.

601
00:27:31,000 --> 00:27:35,000
We need to go back to the treehouse and sort it all out if we need to know more.

602
00:27:35,000 --> 00:27:36,000
Let's go.

603
00:27:37,000 --> 00:27:42,000
Dr. D says that we need to look for loud sounds that could be causing the dogs to bark.

604
00:27:42,000 --> 00:27:44,000
I know one sound that's really loud.

605
00:27:44,000 --> 00:27:46,000
It's a garbage truck, and I know they make dogs bark.

606
00:27:46,000 --> 00:27:47,000
What about sirens?

607
00:27:47,000 --> 00:27:50,000
My dog always barks when he hears a siren.

608
00:27:50,000 --> 00:27:52,000
Yeah, and there's a new factory near a hollow sound.

609
00:27:52,000 --> 00:27:54,000
I bet that's it.

610
00:27:54,000 --> 00:27:56,000
You know, and the stink it was, the candy factory.

611
00:27:56,000 --> 00:27:59,000
Maybe noises from the factory are making the dogs bark.

612
00:27:59,000 --> 00:28:01,000
That should be our hypothesis.

613
00:28:01,000 --> 00:28:03,000
Let's look at these emails.

614
00:28:03,000 --> 00:28:05,000
Wow, lots of dogs are barking in hollow sound.

615
00:28:05,000 --> 00:28:07,000
That's right near the factory.

616
00:28:07,000 --> 00:28:09,000
So that's got to be it.

617
00:28:09,000 --> 00:28:11,000
Oh, this is too easy.

618
00:28:11,000 --> 00:28:12,000
We are so good.

619
00:28:13,000 --> 00:28:14,000
So what's up?

620
00:28:14,000 --> 00:28:16,000
Will the treehouse detectives solve this problem?

621
00:28:16,000 --> 00:28:19,000
Do you think their hypothesis is right or wrong?

622
00:28:19,000 --> 00:28:22,000
Are high and low frequencies an important part of solving this problem?

623
00:28:22,000 --> 00:28:25,000
We'll see you next time for the next NASA Wi-Files,

624
00:28:25,000 --> 00:28:27,000
The Case of the Barking Dog.

625
00:28:31,000 --> 00:28:33,000
Did you watch your dog last night?

626
00:28:33,000 --> 00:28:36,000
I tried to, but I've been so tired, I fell right asleep.

627
00:28:36,000 --> 00:28:39,000
Did you ever hear that sound connectivity Matthew was talking about?

628
00:28:39,000 --> 00:28:41,000
I did. It was a lot of fun.

629
00:28:41,000 --> 00:28:44,000
But I couldn't hear the high frequency noise like that of a dog whistle.

630
00:28:44,000 --> 00:28:46,000
I don't think it'll help us solve the problem.

631
00:28:46,000 --> 00:28:48,000
Oh, well, at least we tried.

632
00:28:48,000 --> 00:28:51,000
But I think we're getting somewhere. Let's get organized.

633
00:28:51,000 --> 00:28:52,000
Why do we need to do that?

634
00:28:52,000 --> 00:28:54,000
We already know what's causing the problem.

635
00:28:54,000 --> 00:28:55,000
It's the factory.

636
00:28:55,000 --> 00:28:58,000
Dr. D told us not to jump to any conclusions.

637
00:28:58,000 --> 00:29:00,000
So let's figure this thing out.

638
00:29:00,000 --> 00:29:02,000
Back to the matrix board.

639
00:29:05,000 --> 00:29:08,000
Across the top are the names of the neighborhoods.

640
00:29:08,000 --> 00:29:09,000
Midnight Growl,

641
00:29:09,000 --> 00:29:11,000
Cochlear Cascade,

642
00:29:11,000 --> 00:29:12,000
Sound Seaside,

643
00:29:12,000 --> 00:29:14,000
and Southern Sleepless Subdivision.

644
00:29:14,000 --> 00:29:17,000
Down the left side, we have one cause,

645
00:29:17,000 --> 00:29:18,000
which is garbage pickup.

646
00:29:18,000 --> 00:29:20,000
And we have the effect of dogs barking.

647
00:29:21,000 --> 00:29:23,000
The trucks were in Midnight Growl on Monday,

648
00:29:23,000 --> 00:29:25,000
and there were dogs barking.

649
00:29:25,000 --> 00:29:27,000
Then, in Sleepless Subdivision,

650
00:29:27,000 --> 00:29:28,000
they were there on Tuesday,

651
00:29:28,000 --> 00:29:30,000
but no dogs were barking.

652
00:29:30,000 --> 00:29:34,000
Okay, in Sound Seaside, they have not yet had garbage pickup.

653
00:29:34,000 --> 00:29:35,000
In Cochlear Cascade,

654
00:29:35,000 --> 00:29:37,000
there was garbage pickup on Wednesday,

655
00:29:37,000 --> 00:29:39,000
and the dogs were still barking.

656
00:29:39,000 --> 00:29:40,000
This is confusing.

657
00:29:40,000 --> 00:29:43,000
The matrix shows us that there is a relationship

658
00:29:43,000 --> 00:29:45,000
between garbage pickup and dogs barking,

659
00:29:45,000 --> 00:29:47,000
but only on two days.

660
00:29:47,000 --> 00:29:49,000
Cochlear Cascade had parking on Monday,

661
00:29:49,000 --> 00:29:51,000
but there was no garbage pickup on that day.

662
00:29:51,000 --> 00:29:52,000
Yeah, and let's remember,

663
00:29:52,000 --> 00:29:54,000
dogs have been barking at night,

664
00:29:54,000 --> 00:29:56,000
and there's no garbage pickup at night.

665
00:29:56,000 --> 00:29:58,000
Maybe we need to rule out garbage trucks.

666
00:29:58,000 --> 00:29:59,000
What about sirens?

667
00:29:59,000 --> 00:30:00,000
Forget it.

668
00:30:00,000 --> 00:30:01,000
Sirens go off all the time,

669
00:30:01,000 --> 00:30:04,000
so why would it be more barking now than before?

670
00:30:04,000 --> 00:30:06,000
I think we need to find a new hypothesis.

671
00:30:11,000 --> 00:30:14,000
Good morning, I am Ted Toon

672
00:30:14,000 --> 00:30:17,000
with the Kids Science News Network News.

673
00:30:17,000 --> 00:30:18,000
The mystery of the barking dogs

674
00:30:18,000 --> 00:30:20,000
continues to confuse authorities.

675
00:30:20,000 --> 00:30:22,000
More dogs were heard barking last night,

676
00:30:22,000 --> 00:30:24,000
and even more people were kept awake

677
00:30:24,000 --> 00:30:26,000
between 10 p.m. and midnight.

678
00:30:26,000 --> 00:30:29,000
We urge you to please bring in those dogs

679
00:30:29,000 --> 00:30:31,000
so that those of us who have to get up in the morning

680
00:30:31,000 --> 00:30:33,000
can get some sleep!

681
00:30:37,000 --> 00:30:38,000
And in consumer news,

682
00:30:38,000 --> 00:30:39,000
the Gum Sonic Company,

683
00:30:39,000 --> 00:30:41,000
makers of the Gum Sonic Turbo,

684
00:30:41,000 --> 00:30:44,000
issued an official product recall today.

685
00:30:44,000 --> 00:30:46,000
Anyone who bought the Gum Sonic Turbo

686
00:30:46,000 --> 00:30:47,000
model electric toothbrush

687
00:30:47,000 --> 00:30:49,000
is urged to return it

688
00:30:49,000 --> 00:30:52,000
to the Gum Sonic Company

689
00:30:52,000 --> 00:30:54,000
for a full refund.

690
00:30:54,000 --> 00:30:57,000
And that's all the news.

691
00:31:00,000 --> 00:31:01,000
I really think we're onto something,

692
00:31:01,000 --> 00:31:02,000
but we need to figure out

693
00:31:02,000 --> 00:31:04,000
where the sound could be coming from.

694
00:31:04,000 --> 00:31:05,000
That's a good idea,

695
00:31:05,000 --> 00:31:06,000
because right now,

696
00:31:06,000 --> 00:31:08,000
we don't know if the sound is coming from outside,

697
00:31:08,000 --> 00:31:09,000
inside our houses,

698
00:31:09,000 --> 00:31:11,000
or even from across town.

699
00:31:11,000 --> 00:31:12,000
Maybe we need to know more about

700
00:31:12,000 --> 00:31:13,000
how fast sound can travel.

701
00:31:13,000 --> 00:31:14,000
Let's experiment.

702
00:31:14,000 --> 00:31:16,000
That's part of the scientific method.

703
00:31:16,000 --> 00:31:18,000
Yeah, maybe our teacher and friends at school can help us.

704
00:31:18,000 --> 00:31:19,000
I'll email my teacher

705
00:31:19,000 --> 00:31:21,000
and ask her if she has any experiments

706
00:31:21,000 --> 00:31:23,000
to help us see how fast sound travels.

707
00:31:23,000 --> 00:31:24,000
Okay.

708
00:31:27,000 --> 00:31:29,000
Good morning, Mrs. Rickles.

709
00:31:29,000 --> 00:31:30,000
Well, good morning.

710
00:31:30,000 --> 00:31:31,000
I've got your email this morning,

711
00:31:31,000 --> 00:31:33,000
and I have just the experiment for you.

712
00:31:33,000 --> 00:31:34,000
I have it all written down here.

713
00:31:34,000 --> 00:31:35,000
Here you go.

714
00:31:35,000 --> 00:31:37,000
Thanks, Mrs. Rickles, for helping us.

715
00:31:37,000 --> 00:31:38,000
You're welcome.

716
00:31:38,000 --> 00:31:39,000
It looks like we need to go outside

717
00:31:39,000 --> 00:31:40,000
and create echoes.

718
00:31:40,000 --> 00:31:43,000
And measure how long it takes us to hear those echoes.

719
00:31:43,000 --> 00:31:44,000
Let's get started.

720
00:31:44,000 --> 00:31:45,000
Okay.

721
00:31:46,000 --> 00:31:48,000
Okay, everybody line up in threes.

722
00:31:48,000 --> 00:31:50,000
One person will do the clapping,

723
00:31:50,000 --> 00:31:52,000
the other person will time the number of claps,

724
00:31:52,000 --> 00:31:54,000
and the other will take the data.

725
00:31:54,000 --> 00:31:56,000
We need a set of pipes,

726
00:31:56,000 --> 00:31:57,000
a meter stick,

727
00:31:57,000 --> 00:31:58,000
a stopwatch,

728
00:31:58,000 --> 00:31:59,000
a pencil and a paper,

729
00:31:59,000 --> 00:32:00,000
and goggles.

730
00:32:00,000 --> 00:32:02,000
We will use the side of the building

731
00:32:02,000 --> 00:32:03,000
to bounce sound off

732
00:32:03,000 --> 00:32:04,000
to create an echo.

733
00:32:04,000 --> 00:32:07,000
Measure 57 meters from that wall.

734
00:32:07,000 --> 00:32:08,000
I can do that,

735
00:32:08,000 --> 00:32:09,000
but I need help.

736
00:32:09,000 --> 00:32:11,000
Help!

737
00:32:14,000 --> 00:32:16,000
Okay, you need to stand right here.

738
00:32:16,000 --> 00:32:18,000
This is where we'll start the experiment.

739
00:32:18,000 --> 00:32:22,000
You need to start clapping these two items together like this

740
00:32:22,000 --> 00:32:24,000
and listen for the echo.

741
00:32:24,000 --> 00:32:25,000
You really need to get a rhythm going

742
00:32:25,000 --> 00:32:28,000
so that you can hear the echo in between claps like this.

743
00:32:30,000 --> 00:32:31,000
Let's try it.

744
00:32:32,000 --> 00:32:33,000
That's good.

745
00:32:34,000 --> 00:32:35,000
Okay, I'm hearing the echo.

746
00:32:35,000 --> 00:32:38,000
Let's time the number of claps in 20 seconds

747
00:32:38,000 --> 00:32:41,000
and measure how long it takes us to hear that echo.

748
00:32:41,000 --> 00:32:43,000
Let's time the number of claps in 20 seconds

749
00:32:43,000 --> 00:32:44,000
and record our data

750
00:32:44,000 --> 00:32:47,000
so we can analyze it when we get back inside.

751
00:32:50,000 --> 00:32:51,000
I have 30 claps.

752
00:32:51,000 --> 00:32:52,000
That's great!

753
00:32:52,000 --> 00:32:53,000
Let's do the experiment again

754
00:32:53,000 --> 00:32:56,000
so we can take an average of the number of claps.

755
00:32:56,000 --> 00:32:58,000
Remember, when you are experimenting,

756
00:32:58,000 --> 00:33:00,000
you must have repeated trials.

757
00:33:00,000 --> 00:33:01,000
In the stink problem,

758
00:33:01,000 --> 00:33:03,000
we learned that we need to perform the experiment

759
00:33:03,000 --> 00:33:05,000
at least three times.

760
00:33:05,000 --> 00:33:08,000
Okay, we need another group to line up.

761
00:33:08,000 --> 00:33:09,000
Let's count down.

762
00:33:09,000 --> 00:33:10,000
Three...

763
00:33:10,000 --> 00:33:11,000
Two...

764
00:33:11,000 --> 00:33:12,000
One...

765
00:33:12,000 --> 00:33:13,000
Go!

766
00:33:27,000 --> 00:33:29,000
Do you know why it's important to take an average?

767
00:33:29,000 --> 00:33:32,000
Taking an average helps us to eliminate the possibility

768
00:33:32,000 --> 00:33:34,000
that someone counted wrong,

769
00:33:34,000 --> 00:33:36,000
read the stopwatch wrong,

770
00:33:36,000 --> 00:33:38,000
or didn't understand the instructions.

771
00:33:39,000 --> 00:33:41,000
Do you know how to calculate an average?

772
00:33:41,000 --> 00:33:42,000
It's easy.

773
00:33:42,000 --> 00:33:46,000
For example, you can take the numbers 20, 22, and 19.

774
00:33:46,000 --> 00:33:48,000
You add them up and divide them by 3,

775
00:33:48,000 --> 00:33:50,000
and that's your average.

776
00:33:50,000 --> 00:33:52,000
Now to calculate the speed of sound,

777
00:33:52,000 --> 00:33:54,000
we need to take the number of seconds

778
00:33:54,000 --> 00:33:57,000
and we need to divide it by the number of claps.

779
00:33:57,000 --> 00:34:00,000
This is going to tell us the amount of time between claps.

780
00:34:00,000 --> 00:34:02,000
What do we get?

781
00:34:02,000 --> 00:34:04,000
That's 0.66.

782
00:34:04,000 --> 00:34:05,000
Let's see.

783
00:34:05,000 --> 00:34:09,000
I calculate that to be two-thirds of a second between claps.

784
00:34:10,000 --> 00:34:14,000
Okay, we have two-thirds of a second between claps,

785
00:34:14,000 --> 00:34:17,000
and the echo comes halfway between claps.

786
00:34:17,000 --> 00:34:19,000
Then it only takes one-third of a second

787
00:34:19,000 --> 00:34:22,000
for the sound to travel to the wall and back to us.

788
00:34:22,000 --> 00:34:24,000
I guess that sounds correct.

789
00:34:24,000 --> 00:34:26,000
And to figure out how far it travels

790
00:34:26,000 --> 00:34:28,000
from us to the wall and back,

791
00:34:28,000 --> 00:34:31,000
wouldn't we just take 57 meters and double it?

792
00:34:31,000 --> 00:34:34,000
What? 114 meters?

793
00:34:34,000 --> 00:34:35,000
Correct.

794
00:34:35,000 --> 00:34:37,000
Now to figure out the speed,

795
00:34:37,000 --> 00:34:39,000
divide distance traveled by the time.

796
00:34:39,000 --> 00:34:42,000
Okay, that would be 114 meters

797
00:34:42,000 --> 00:34:44,000
divided by one-third of a second.

798
00:34:44,000 --> 00:34:47,000
That comes to 342 meters per second.

799
00:34:47,000 --> 00:34:50,000
That's beyond fast.

800
00:34:50,000 --> 00:34:52,000
A meter is just a little longer than a yard.

801
00:34:52,000 --> 00:34:54,000
This means that sound travels

802
00:34:54,000 --> 00:34:56,000
more than three football fields in a second.

803
00:34:56,000 --> 00:34:59,000
Wow, that's really fast.

804
00:34:59,000 --> 00:35:02,000
Now we actually saw how fast sound travels.

805
00:35:02,000 --> 00:35:04,000
Let's go tell Dr. D.

806
00:35:04,000 --> 00:35:06,000
Hey, Dr. D.

807
00:35:06,000 --> 00:35:08,000
Oh, hi, kids.

808
00:35:08,000 --> 00:35:11,000
Dr. D, I did this really cool experiment at school,

809
00:35:11,000 --> 00:35:14,000
and it showed that sound traveled so fast.

810
00:35:14,000 --> 00:35:16,000
What do you think affects how fast sound travels?

811
00:35:16,000 --> 00:35:19,000
Oh, you mean, what are the variables?

812
00:35:19,000 --> 00:35:20,000
Ah, very good.

813
00:35:20,000 --> 00:35:22,000
Could it have anything to do with the temperature?

814
00:35:22,000 --> 00:35:23,000
That's a great question.

815
00:35:23,000 --> 00:35:25,000
The speed of sound increases with temperature.

816
00:35:25,000 --> 00:35:26,000
That's one variable.

817
00:35:26,000 --> 00:35:28,000
Another variable is the moisture.

818
00:35:28,000 --> 00:35:30,000
I guess this means that on hot, humid days,

819
00:35:30,000 --> 00:35:32,000
when it's really sticky outside,

820
00:35:32,000 --> 00:35:34,000
the sound travels really fast.

821
00:35:34,000 --> 00:35:35,000
No, not that much faster.

822
00:35:35,000 --> 00:35:37,000
The material that sound travels through,

823
00:35:37,000 --> 00:35:39,000
which we call the medium, makes a big difference.

824
00:35:39,000 --> 00:35:42,000
Generally, sounds travel faster through liquids

825
00:35:42,000 --> 00:35:43,000
than they do through air.

826
00:35:43,000 --> 00:35:45,000
They travel faster through solids than through liquids.

827
00:35:45,000 --> 00:35:47,000
Why does that happen?

828
00:35:47,000 --> 00:35:48,000
It's called elasticity.

829
00:35:48,000 --> 00:35:49,000
I'll show you how it works.

830
00:35:49,000 --> 00:35:50,000
I'm doing an experiment.

831
00:35:50,000 --> 00:35:51,000
Matthew, why don't you finish

832
00:35:51,000 --> 00:35:53,000
lining up the dominoes on the table,

833
00:35:53,000 --> 00:35:54,000
if you would, please.

834
00:35:54,000 --> 00:35:57,000
Sure.

835
00:35:57,000 --> 00:35:59,000
Bianca, grab ahold of this spring

836
00:35:59,000 --> 00:36:01,000
and hold on really tight.

837
00:36:01,000 --> 00:36:04,000
I'm going to send a wave pulse down the spring.

838
00:36:04,000 --> 00:36:08,000
Pay careful attention to how fast it's going.

839
00:36:08,000 --> 00:36:09,000
All right.

840
00:36:09,000 --> 00:36:13,000
Now, solids and liquids are more elastic than gases.

841
00:36:13,000 --> 00:36:15,000
See how much of a difference this makes?

842
00:36:15,000 --> 00:36:18,000
I'm going to increase the elasticity of this spring

843
00:36:18,000 --> 00:36:19,000
by increasing its tension.

844
00:36:19,000 --> 00:36:21,000
Elasticity tells me how fast

845
00:36:21,000 --> 00:36:23,000
things are brought back into place

846
00:36:23,000 --> 00:36:24,000
when they're disturbed.

847
00:36:24,000 --> 00:36:25,000
Are you ready?

848
00:36:25,000 --> 00:36:29,000
Watch carefully.

849
00:36:29,000 --> 00:36:31,000
Wow, it's really moving.

850
00:36:31,000 --> 00:36:33,000
Notice how the wave, or energy,

851
00:36:33,000 --> 00:36:34,000
travels through the spring,

852
00:36:34,000 --> 00:36:35,000
but the spring doesn't go anywhere.

853
00:36:35,000 --> 00:36:37,000
It just vibrates in place.

854
00:36:37,000 --> 00:36:39,000
It's like the dominoes that Matthew just set up.

855
00:36:39,000 --> 00:36:41,000
When he knocks over the first one,

856
00:36:41,000 --> 00:36:43,000
the energy will travel through,

857
00:36:43,000 --> 00:36:46,000
but the individual dominoes just move a little bit.

858
00:36:46,000 --> 00:36:47,000
Try it, Matthew.

859
00:36:47,000 --> 00:36:54,000
Okay.

860
00:36:54,000 --> 00:36:55,000
Cool.

861
00:36:55,000 --> 00:36:56,000
Now we know that sound gets softer

862
00:36:56,000 --> 00:36:57,000
as it travels away from a source.

863
00:36:57,000 --> 00:36:59,000
When sound travels from medium,

864
00:36:59,000 --> 00:37:01,000
the molecules vibrate in place,

865
00:37:01,000 --> 00:37:02,000
but don't really go anywhere.

866
00:37:02,000 --> 00:37:04,000
What else do we know about sound?

867
00:37:04,000 --> 00:37:07,000
Well, we know the medium affects how fast sound travels.

868
00:37:07,000 --> 00:37:10,000
We also know it influences how far sound goes.

869
00:37:10,000 --> 00:37:11,000
But I thought we already talked about

870
00:37:11,000 --> 00:37:13,000
how sound died off in the distance

871
00:37:13,000 --> 00:37:15,000
when we were in that room with all the sponges.

872
00:37:15,000 --> 00:37:16,000
Well, that's right.

873
00:37:16,000 --> 00:37:18,000
We discussed how sound gets softer with distance

874
00:37:18,000 --> 00:37:20,000
because the waves spread out.

875
00:37:20,000 --> 00:37:23,000
Is that like when you throw a rock into a pond of water

876
00:37:23,000 --> 00:37:26,000
and the circles get bigger as they move away from the splash?

877
00:37:26,000 --> 00:37:27,000
Exactly.

878
00:37:27,000 --> 00:37:28,000
But in addition to that,

879
00:37:28,000 --> 00:37:30,000
the medium affects how far sound travels

880
00:37:30,000 --> 00:37:32,000
by absorbing the sound energy.

881
00:37:32,000 --> 00:37:35,000
I have a friend over at NASA who specializes in acoustics.

882
00:37:35,000 --> 00:37:37,000
Her name is Dr. Christine Darden.

883
00:37:37,000 --> 00:37:38,000
You should go talk with her.

884
00:37:38,000 --> 00:37:39,000
She can help you to understand

885
00:37:39,000 --> 00:37:42,000
how the medium affects how far sound travels.

886
00:37:42,000 --> 00:37:45,000
Maybe we can dial her up when we get back to the treehouse.

887
00:37:45,000 --> 00:37:47,000
Thanks for all your help, Dr. D.

888
00:37:47,000 --> 00:37:48,000
See you.

889
00:37:48,000 --> 00:37:49,000
Bye.

890
00:37:49,000 --> 00:37:51,000
Bye, guys.

891
00:37:51,000 --> 00:37:53,000
Computer, get us Dr. Christine Darden

892
00:37:53,000 --> 00:37:55,000
at NASA Langley Research Center.

893
00:37:58,000 --> 00:37:59,000
Oh.

894
00:37:59,000 --> 00:38:00,000
Hi, kids.

895
00:38:00,000 --> 00:38:01,000
I'm Dr. Darden,

896
00:38:01,000 --> 00:38:04,000
an engineer here at NASA Langley Research Center.

897
00:38:04,000 --> 00:38:07,000
I've done sonic boom research here for many, many years.

898
00:38:07,000 --> 00:38:09,000
What's a sonic boom?

899
00:38:09,000 --> 00:38:12,000
Doesn't it have to do with the speed of airplanes?

900
00:38:12,000 --> 00:38:13,000
Yes, it does.

901
00:38:13,000 --> 00:38:15,000
A sonic boom occurs when an airplane

902
00:38:15,000 --> 00:38:18,000
travels faster than the speed of sound.

903
00:38:18,000 --> 00:38:22,000
We do lots of sonic boom testing in this wind tunnel.

904
00:38:22,000 --> 00:38:24,000
In fact, the first models that we used

905
00:38:24,000 --> 00:38:27,000
were no larger than my fingernail.

906
00:38:27,000 --> 00:38:29,000
When an airplane travels through the air,

907
00:38:29,000 --> 00:38:31,000
it generates pressure waves that travel

908
00:38:31,000 --> 00:38:34,000
at the speed of sound in all directions.

909
00:38:34,000 --> 00:38:36,000
A plane flying at the speed of sound

910
00:38:36,000 --> 00:38:39,000
moves at the same speed as the disturbances,

911
00:38:39,000 --> 00:38:41,000
causing a shock wave to form.

912
00:38:41,000 --> 00:38:44,000
When the plane flies faster than the speed of sound,

913
00:38:44,000 --> 00:38:47,000
this shock wave forms a cone shape

914
00:38:47,000 --> 00:38:49,000
attached to the nose of the airplane.

915
00:38:49,000 --> 00:38:52,000
Air pressure just inside the cone is high,

916
00:38:52,000 --> 00:38:55,000
and air pressure ahead of the cone is normal.

917
00:38:55,000 --> 00:38:58,000
This shock wave, or cone, extends to the ground,

918
00:38:58,000 --> 00:39:01,000
perhaps 10 to 15 miles.

919
00:39:01,000 --> 00:39:04,000
The sonic boom is heard when the sudden change in pressure

920
00:39:04,000 --> 00:39:06,000
crosses your ear.

921
00:39:06,000 --> 00:39:09,000
Let me demonstrate for you with this balloon.

922
00:39:09,000 --> 00:39:11,000
The air pressure inside this balloon

923
00:39:11,000 --> 00:39:14,000
is higher than the air pressure outside the balloon.

924
00:39:14,000 --> 00:39:15,000
If I pop the balloon,

925
00:39:15,000 --> 00:39:18,000
a shock wave is generated much like a sonic boom.

926
00:39:18,000 --> 00:39:20,000
Could there be a very high-frequency sound

927
00:39:20,000 --> 00:39:22,000
that people can't hear but dogs can?

928
00:39:22,000 --> 00:39:24,000
Absolutely, but remember,

929
00:39:24,000 --> 00:39:27,000
that very high-frequency sound can't come from far away.

930
00:39:27,000 --> 00:39:30,000
Because high-frequency sounds don't travel very far.

931
00:39:30,000 --> 00:39:31,000
That's right.

932
00:39:31,000 --> 00:39:33,000
Thanks, Dr. Darden.

933
00:39:33,000 --> 00:39:34,000
You're welcome.

934
00:39:34,000 --> 00:39:36,000
Goodbye, and good luck.

935
00:39:36,000 --> 00:39:41,000
Well, we have already eliminated garbage trucks and sirens

936
00:39:41,000 --> 00:39:43,000
and most other loud noises.

937
00:39:43,000 --> 00:39:45,000
The factory is still a possibility.

938
00:39:45,000 --> 00:39:47,000
But people haven't come playing yet,

939
00:39:47,000 --> 00:39:49,000
so it must be a very high-frequency sound.

940
00:39:49,000 --> 00:39:53,000
And besides, very high-frequency sounds can't travel very far,

941
00:39:53,000 --> 00:39:55,000
so it can't be the factory.

942
00:39:55,000 --> 00:39:57,000
So I guess our hypothesis of the factory is wrong.

943
00:39:57,000 --> 00:39:59,000
It's back to the drawing board.

944
00:39:59,000 --> 00:40:01,000
Maybe we need to find something close to our houses

945
00:40:01,000 --> 00:40:04,000
or even inside our houses that make a high-frequency noise.

946
00:40:04,000 --> 00:40:05,000
How are we supposed to do that?

947
00:40:05,000 --> 00:40:07,000
We can't even hear high-frequency noises.

948
00:40:07,000 --> 00:40:09,000
Remember those dog whistles?

949
00:40:09,000 --> 00:40:10,000
They are high-frequency.

950
00:40:10,000 --> 00:40:11,000
Yes.

951
00:40:11,000 --> 00:40:12,000
Let's check that out.

952
00:40:12,000 --> 00:40:13,000
Let's check that out tomorrow.

953
00:40:13,000 --> 00:40:15,000
Sounds good to me.

954
00:40:15,000 --> 00:40:16,000
So what's up?

955
00:40:16,000 --> 00:40:19,000
Do you think dog whistles are the source of the problem?

956
00:40:19,000 --> 00:40:21,000
Are the dogs hearing a sound from inside their house,

957
00:40:21,000 --> 00:40:24,000
or could there be an outside source for this problem?

958
00:40:24,000 --> 00:40:27,000
Don't miss the final episode of the NASA Y-Files,

959
00:40:27,000 --> 00:40:29,000
The Case of the Barking Dogs.

960
00:40:34,000 --> 00:40:35,000
Okay, thank you.

961
00:40:35,000 --> 00:40:37,000
Bye-bye.

962
00:40:37,000 --> 00:40:38,000
Well, that's it.

963
00:40:38,000 --> 00:40:40,000
I called the last pet store.

964
00:40:40,000 --> 00:40:43,000
Most of them said they haven't sold any dog whistles recently,

965
00:40:43,000 --> 00:40:46,000
and some of them said they never even carry dog whistles.

966
00:40:46,000 --> 00:40:47,000
Great!

967
00:40:47,000 --> 00:40:50,000
This means we can cross off high-frequency sound as a hypothesis.

968
00:40:50,000 --> 00:40:53,000
No, it means we can cross off dog whistles.

969
00:40:53,000 --> 00:40:55,000
Have you figured out the answer yet?

970
00:40:55,000 --> 00:40:56,000
We could use your help.

971
00:40:56,000 --> 00:40:57,000
This is really hard.

972
00:40:57,000 --> 00:40:59,000
We're never going to figure out why the dogs are barking,

973
00:40:59,000 --> 00:41:02,000
and I'm never going to get any sleep.

974
00:41:02,000 --> 00:41:03,000
Okay, let's think.

975
00:41:03,000 --> 00:41:06,000
We've learned a lot, but we still don't know what the answer is.

976
00:41:06,000 --> 00:41:08,000
It could be an inside noise,

977
00:41:08,000 --> 00:41:12,000
or, let me think, a coffee grinder or blender?

978
00:41:12,000 --> 00:41:15,000
Yeah, even my mom's blender makes a lot of noise.

979
00:41:15,000 --> 00:41:17,000
No, I don't think it could be a coffee grinder or blender,

980
00:41:17,000 --> 00:41:19,000
because they've been around for a long time.

981
00:41:19,000 --> 00:41:21,000
This is so hard.

982
00:41:21,000 --> 00:41:23,000
Remember what Dr. D says,

983
00:41:23,000 --> 00:41:26,000
never give up, because the answer could be right in front of us.

984
00:41:26,000 --> 00:41:29,000
Really, all I see in front of me is Jacob.

985
00:41:29,000 --> 00:41:31,000
Okay, you guys, knock it off.

986
00:41:31,000 --> 00:41:33,000
We need to get back to our neat snowboard.

987
00:41:35,000 --> 00:41:37,000
We now know it's not dog whistles.

988
00:41:37,000 --> 00:41:41,000
But it's strange, because both the dogs inside and outside are barking.

989
00:41:41,000 --> 00:41:43,000
It still could be a high-frequency sound.

990
00:41:43,000 --> 00:41:46,000
But high-frequency sounds don't travel very far.

991
00:41:46,000 --> 00:41:50,000
We also know that sounds can travel through a solid liquid nanogas.

992
00:41:50,000 --> 00:41:53,000
So we need to know which things make high-frequency sounds.

993
00:41:53,000 --> 00:41:55,000
Who should we ask?

994
00:41:55,000 --> 00:41:56,000
Let's do an Internet search.

995
00:41:56,000 --> 00:41:58,000
More research.

996
00:41:58,000 --> 00:42:00,000
Yes, but this research is fun.

997
00:42:02,000 --> 00:42:04,000
Look at these animals that use high frequencies.

998
00:42:04,000 --> 00:42:07,000
Bats, dolphins, that's interesting.

999
00:42:07,000 --> 00:42:09,000
Hey, we're learning about bats in school.

1000
00:42:09,000 --> 00:42:11,000
Maybe we could go to a museum.

1001
00:42:11,000 --> 00:42:13,000
I think I'll stay here and look at this research.

1002
00:42:13,000 --> 00:42:14,000
I'll stay with you.

1003
00:42:14,000 --> 00:42:17,000
Okay, I'll get one of the other treehouse detectives to come with me.

1004
00:42:25,000 --> 00:42:27,000
You do look like you're looking for something.

1005
00:42:27,000 --> 00:42:29,000
My name is Mrs. Chris Lewis. Can I help you?

1006
00:42:29,000 --> 00:42:31,000
Hi, I'm Matthew, and this is Catherine.

1007
00:42:31,000 --> 00:42:33,000
And we're working on a problem.

1008
00:42:33,000 --> 00:42:38,000
It's a sound problem, and we really need to learn more about how high-frequency travels.

1009
00:42:38,000 --> 00:42:39,000
I may be able to help you.

1010
00:42:39,000 --> 00:42:42,000
Let me show you something that uses high-frequency sound.

1011
00:42:43,000 --> 00:42:46,000
Let me introduce you to a big brown bat.

1012
00:42:46,000 --> 00:42:48,000
Wow, does he bite?

1013
00:42:48,000 --> 00:42:50,000
No, you can touch him gently if you'd like.

1014
00:42:50,000 --> 00:42:53,000
Do bats use high-frequency sounds?

1015
00:42:53,000 --> 00:42:55,000
Sure, bats hunt in the dark.

1016
00:42:55,000 --> 00:42:59,000
They use high-frequency sounds and listen for the echoes in order to navigate and find food.

1017
00:42:59,000 --> 00:43:00,000
That's great.

1018
00:43:00,000 --> 00:43:03,000
We heard that high-frequency sounds don't travel very far.

1019
00:43:03,000 --> 00:43:05,000
Is that true for bats?

1020
00:43:05,000 --> 00:43:09,000
Yes, that's true. Air absorbs sound, especially high-frequency sound.

1021
00:43:09,000 --> 00:43:14,000
Some bats can hear things 60 feet away, but the average is only about 15 feet away.

1022
00:43:15,000 --> 00:43:19,000
In school, we just did an experiment on how fast sound travels.

1023
00:43:19,000 --> 00:43:22,000
This sounds amazing, but does it really help the bats?

1024
00:43:22,000 --> 00:43:23,000
Oh, yes, it does.

1025
00:43:23,000 --> 00:43:29,000
A bat can tell the speed and direction of a moving object, whether it's alive or not, even if it's hard or soft.

1026
00:43:29,000 --> 00:43:32,000
In fact, in a perfectly dark room very much like this,

1027
00:43:32,000 --> 00:43:38,000
a bat can fly through without running into a moving wire that's as thin as a human hair.

1028
00:43:38,000 --> 00:43:43,000
In fact, a big brown bat can catch up to 600 mosquitoes in one hour.

1029
00:43:43,000 --> 00:43:45,000
600 mosquitoes an hour?

1030
00:43:45,000 --> 00:43:46,000
Doesn't that seem incredible?

1031
00:43:46,000 --> 00:43:47,000
Yeah.

1032
00:43:47,000 --> 00:43:50,000
Thanks, Mrs. Lewis. That was so fun.

1033
00:43:50,000 --> 00:43:51,000
Bye. Good luck.

1034
00:43:51,000 --> 00:43:52,000
Bye.

1035
00:43:52,000 --> 00:43:56,000
Now we need to figure out how to tell which things are making high-frequency noises.

1036
00:43:56,000 --> 00:43:57,000
Yeah, you're right.

1037
00:43:57,000 --> 00:43:58,000
Come on.

1038
00:44:00,000 --> 00:44:03,000
How do we figure out what's making these high-frequency sounds?

1039
00:44:03,000 --> 00:44:08,000
Let's do an Internet search and try to find a list of things that make high-frequency sounds.

1040
00:44:08,000 --> 00:44:09,000
Look up high-frequency.

1041
00:44:09,000 --> 00:44:10,000
How do I do that?

1042
00:44:10,000 --> 00:44:13,000
Just type in high-frequency sound.

1043
00:44:13,000 --> 00:44:14,000
That's pretty cool.

1044
00:44:14,000 --> 00:44:16,000
Have you ever started that?

1045
00:44:16,000 --> 00:44:18,000
Oh, look. Here it is.

1046
00:44:18,000 --> 00:44:21,000
Wow. What's an electronic dog repeller?

1047
00:44:21,000 --> 00:44:23,000
An electronic dog fight stopper.

1048
00:44:23,000 --> 00:44:24,000
That sounds weird.

1049
00:44:24,000 --> 00:44:27,000
And a pest zapper?

1050
00:44:27,000 --> 00:44:28,000
A toothbrush?

1051
00:44:28,000 --> 00:44:31,000
I didn't know toothbrushes had high-frequency sounds.

1052
00:44:31,000 --> 00:44:32,000
Those are electric ones.

1053
00:44:32,000 --> 00:44:33,000
Oh.

1054
00:44:33,000 --> 00:44:34,000
I wouldn't know much about that.

1055
00:44:34,000 --> 00:44:37,000
I had to brush my teeth by hand.

1056
00:44:37,000 --> 00:44:38,000
What should we do with this?

1057
00:44:38,000 --> 00:44:41,000
Let's email all the people who responded to our first email.

1058
00:44:41,000 --> 00:44:45,000
Let's ask them if they have any of these weird electronic devices.

1059
00:44:45,000 --> 00:44:46,000
That's a great idea.

1060
00:44:46,000 --> 00:44:47,000
Let's get busy.

1061
00:44:50,000 --> 00:44:52,000
Hey, guys. What are you doing today?

1062
00:44:52,000 --> 00:44:54,000
Oh, we're just playing around in your lab.

1063
00:44:54,000 --> 00:44:55,000
Just kidding.

1064
00:44:55,000 --> 00:44:58,000
We have a list of things that make high-frequency noises.

1065
00:44:58,000 --> 00:45:00,000
But we're not sure if we're on the right track.

1066
00:45:00,000 --> 00:45:02,000
We're hoping you can help us decide what we need to do next.

1067
00:45:02,000 --> 00:45:04,000
Let's review what we know.

1068
00:45:04,000 --> 00:45:06,000
We know that dogs can hear at very high frequencies,

1069
00:45:06,000 --> 00:45:08,000
much higher than human beings can hear.

1070
00:45:08,000 --> 00:45:12,000
At the museum, the bat creator told us that high-frequency sounds don't travel very far.

1071
00:45:12,000 --> 00:45:16,000
High and low-frequency sound travel is a really easy concept.

1072
00:45:16,000 --> 00:45:18,000
Do you have an experiment for us?

1073
00:45:18,000 --> 00:45:19,000
I certainly do.

1074
00:45:19,000 --> 00:45:21,000
In fact, I could do a little show-and-tell.

1075
00:45:21,000 --> 00:45:23,000
Would you like me to come to your class?

1076
00:45:23,000 --> 00:45:24,000
Yes, you can come to our class.

1077
00:45:24,000 --> 00:45:25,000
Oh, that would be great.

1078
00:45:30,000 --> 00:45:32,000
Boys and girls, this is Dr. D.

1079
00:45:32,000 --> 00:45:35,000
He's brought something really special to share with us today.

1080
00:45:35,000 --> 00:45:36,000
Good morning.

1081
00:45:36,000 --> 00:45:38,000
Good morning.

1082
00:45:38,000 --> 00:45:40,000
I already have an experiment set up.

1083
00:45:40,000 --> 00:45:43,000
It's going to show you the difference between high and low-frequency sounds.

1084
00:45:43,000 --> 00:45:45,000
Will we be able to see anything?

1085
00:45:45,000 --> 00:45:47,000
No, but you'll be able to hear it.

1086
00:45:47,000 --> 00:45:50,000
This machine is going to produce sounds at different frequencies.

1087
00:45:50,000 --> 00:45:53,000
I want you to raise your hand when you can't hear the sound anymore.

1088
00:45:53,000 --> 00:45:56,000
This is going to give you an idea about high and low-frequency sounds.

1089
00:45:57,000 --> 00:45:58,000
Here we go.

1090
00:46:16,000 --> 00:46:18,000
Oh, looks like we lost your teacher first.

1091
00:46:18,000 --> 00:46:19,000
I can't hear it either.

1092
00:46:19,000 --> 00:46:22,000
When you get older, you can't hear high-frequency sounds as well.

1093
00:46:22,000 --> 00:46:23,000
Let's keep going.

1094
00:46:30,000 --> 00:46:32,000
Ah, no one can hear it now.

1095
00:46:32,000 --> 00:46:34,000
I bet your dogs can still hear it.

1096
00:46:34,000 --> 00:46:36,000
Now we'll need some volunteers.

1097
00:46:36,000 --> 00:46:40,000
I'll take you and you and you and you.

1098
00:46:43,000 --> 00:46:46,000
I'm going to transmit a low-frequency sound to you.

1099
00:46:46,000 --> 00:46:50,000
PJ's going to put the phone between the speaker and your ear a couple of times.

1100
00:46:50,000 --> 00:46:51,000
Let's do it.

1101
00:46:53,000 --> 00:46:55,000
What happened?

1102
00:46:55,000 --> 00:46:57,000
The sound wasn't as loud.

1103
00:46:57,000 --> 00:47:00,000
Now I'm going to transmit a higher-frequency sound.

1104
00:47:07,000 --> 00:47:09,000
What happened this time?

1105
00:47:09,000 --> 00:47:12,000
It seemed like the sound was blocked off a lot more.

1106
00:47:12,000 --> 00:47:14,000
Let's try it again. Why don't you two switch places?

1107
00:47:14,000 --> 00:47:15,000
Okay.

1108
00:47:16,000 --> 00:47:21,000
Now PJ, did both sounds get softer when Jacob put the phonebook between the speaker and your ear?

1109
00:47:21,000 --> 00:47:24,000
Yes, but the higher-frequency sounds were a lot softer.

1110
00:47:24,000 --> 00:47:26,000
Now I'm going to transmit a higher-frequency sound.

1111
00:47:26,000 --> 00:47:28,000
What happened this time?

1112
00:47:28,000 --> 00:47:31,000
It seemed like the sound was blocked off a lot more.

1113
00:47:31,000 --> 00:47:33,000
Let's try it again. Why don't you two switch places?

1114
00:47:33,000 --> 00:47:34,000
Okay.

1115
00:47:46,000 --> 00:47:48,000
Why do you think so?

1116
00:47:48,000 --> 00:47:51,000
I don't know. Maybe you put the book closer to my ear.

1117
00:47:51,000 --> 00:47:54,000
The book was the same distance both times.

1118
00:47:54,000 --> 00:47:59,000
Remember, with the scientific method, we can only change one variable at a time.

1119
00:47:59,000 --> 00:48:04,000
I changed the frequency, so I'm glad Jacob was careful to keep the book distance the same both times.

1120
00:48:04,000 --> 00:48:08,000
I think that low-frequency sounds travel better than high-frequency sounds.

1121
00:48:08,000 --> 00:48:13,000
Well, low-frequency sounds do bend around corners a lot easier than high-frequency sounds.

1122
00:48:13,000 --> 00:48:18,000
That's why the lower-frequency sound was a little clearer because it bent around the phonebook.

1123
00:48:18,000 --> 00:48:20,000
This is so cool!

1124
00:48:20,000 --> 00:48:25,000
This experiment taught us that high-frequency sounds don't bend around corners very easily.

1125
00:48:25,000 --> 00:48:27,000
Don't forget what we learned about the bats.

1126
00:48:27,000 --> 00:48:29,000
How could we forget?

1127
00:48:29,000 --> 00:48:31,000
High-frequency bat calls don't travel very far.

1128
00:48:31,000 --> 00:48:33,000
What does all this mean?

1129
00:48:33,000 --> 00:48:37,000
Let's go back to our treehouse after school and think about it.

1130
00:48:39,000 --> 00:48:41,000
It's too bad PJ couldn't make it to the treehouse.

1131
00:48:41,000 --> 00:48:43,000
That sure was a great show and tell we had at school.

1132
00:48:43,000 --> 00:48:47,000
It really made it clear to me that high-frequency sounds don't bend around corners easily.

1133
00:48:47,000 --> 00:48:48,000
They only go in a straight line.

1134
00:48:48,000 --> 00:48:50,000
Let's get back to our need-to-know board.

1135
00:48:50,000 --> 00:48:53,000
We know that high-frequency sounds don't travel very far.

1136
00:48:53,000 --> 00:48:57,000
We know that it's not a low-frequency sound because humans aren't complaining about it.

1137
00:48:57,000 --> 00:48:59,000
We learned that from Ms. Sullivan at NASA.

1138
00:48:59,000 --> 00:49:02,000
We also know that high-frequency sounds can come from inside the house.

1139
00:49:02,000 --> 00:49:04,000
Remember our list?

1140
00:49:04,000 --> 00:49:10,000
We also need to know which neighborhoods are hearing barking and the item that is making the high-frequency sound.

1141
00:49:11,000 --> 00:49:13,000
Wow, look at all the emails we've received.

1142
00:49:13,000 --> 00:49:15,000
We better start separating them out.

1143
00:49:15,000 --> 00:49:18,000
I divided them into piles by subdivision.

1144
00:49:18,000 --> 00:49:20,000
Let's put them on a matrix board.

1145
00:49:20,000 --> 00:49:22,000
Oh, great, another matrix.

1146
00:49:22,000 --> 00:49:25,000
Hey, a matrix board can help you sort your information.

1147
00:49:25,000 --> 00:49:27,000
It may look hard, but don't sweat it.

1148
00:49:27,000 --> 00:49:29,000
Okay, okay, okay, let's get started.

1149
00:49:31,000 --> 00:49:34,000
On the matrix board, across the top, we have the subdivisions.

1150
00:49:34,000 --> 00:49:36,000
Midnight growl.

1151
00:49:36,000 --> 00:49:38,000
Cochlea cascade.

1152
00:49:38,000 --> 00:49:40,000
Sound seaside.

1153
00:49:40,000 --> 00:49:42,000
And the southern sleepless division.

1154
00:49:42,000 --> 00:49:45,000
Now down the side, let's put the possible causes.

1155
00:49:45,000 --> 00:49:50,000
Dog repellers, dog fight stoppers, pest zappers, and electronic toothbrushes.

1156
00:49:50,000 --> 00:49:53,000
Also on the side, let's put the effects.

1157
00:49:53,000 --> 00:49:55,000
Barking in the day and barking in the night.

1158
00:49:55,000 --> 00:49:59,000
Okay, in midnight growl, they still have dogs barking.

1159
00:49:59,000 --> 00:50:02,000
And they have dog repellers and toothbrushes.

1160
00:50:02,000 --> 00:50:07,000
And in the southern sleepless division, they have dogs barking and toothbrushes.

1161
00:50:07,000 --> 00:50:12,000
But on sound seaside, they have toothbrushes, but no dogs barking, so it can't be a toothbrush.

1162
00:50:12,000 --> 00:50:15,000
Let's not jump to conclusions before we analyze the data.

1163
00:50:15,000 --> 00:50:18,000
Analyzing the data could be a key to solving the problem.

1164
00:50:18,000 --> 00:50:27,000
In Cochlea cascade, they have dogs barking, dog repellers, dog fight stoppers, pest zappers, and toothbrushes.

1165
00:50:27,000 --> 00:50:29,000
Hmm, interesting, but I still don't get it.

1166
00:50:29,000 --> 00:50:33,000
The list is too long. I wouldn't want to have to test all those items.

1167
00:50:38,000 --> 00:50:42,000
I'm a well-rested Ted Toon with this special report.

1168
00:50:42,000 --> 00:50:48,000
Kids Science News Network has learned that bringing the barking dogs inside your house will only make the barking worse.

1169
00:50:48,000 --> 00:50:54,000
Whatever is making the dogs bark is definitely inside the houses of the residents of the city.

1170
00:50:54,000 --> 00:50:56,000
Not that I have to worry about it anymore.

1171
00:50:56,000 --> 00:50:58,000
More after this.

1172
00:50:58,000 --> 00:51:04,000
Wow, if the people took their dogs inside and the barking got worse, then maybe the sound is coming from inside the house.

1173
00:51:04,000 --> 00:51:07,000
Yeah, but what about the dogs that are barking outside?

1174
00:51:07,000 --> 00:51:11,000
The dogs inside probably made the dogs outside start barking.

1175
00:51:11,000 --> 00:51:13,000
You know, dogs respond to other dogs.

1176
00:51:13,000 --> 00:51:20,000
For a further report on the Gumsonic product recall, we go live to KSNN on-the-scene reporter, I Am Listening.

1177
00:51:20,000 --> 00:51:23,000
Thanks, Ted. Gumsonic issued a product recall.

1178
00:51:23,000 --> 00:51:24,000
Go ahead, I Am.

1179
00:51:24,000 --> 00:51:25,000
Ted, I already started.

1180
00:51:25,000 --> 00:51:26,000
Can she hear me?

1181
00:51:26,000 --> 00:51:27,000
Ted!

1182
00:51:27,000 --> 00:51:30,000
Oh, sorry, I Am. Please, go ahead.

1183
00:51:30,000 --> 00:51:39,000
As I was saying, Ted, Gumsonic issued a product recall for defective Gumsonic Turbo Model electric toothbrushes just days ago.

1184
00:51:39,000 --> 00:51:45,000
However, they have been unable to contact their best salesman, Mr. Big T.

1185
00:51:45,000 --> 00:51:52,000
Mr. Big T is currently selling the toothbrushes during a week-long Gumsonic door-to-door sales campaign.

1186
00:51:52,000 --> 00:51:54,000
If you happen to see Mr. T, please call...

1187
00:51:54,000 --> 00:51:57,000
Thanks, I Am. That was reporter, I Am Listening, on the scene.

1188
00:51:57,000 --> 00:51:58,000
I wasn't finished.

1189
00:51:58,000 --> 00:51:59,000
We'll be back after a message from...

1190
00:51:59,000 --> 00:52:00,000
Ted!

1191
00:52:00,000 --> 00:52:04,000
Oh, my mom bought one of those toothbrushes. Let's go to my house and check it out.

1192
00:52:04,000 --> 00:52:05,000
Okay.

1193
00:52:07,000 --> 00:52:09,000
I don't hear anything that annoying.

1194
00:52:09,000 --> 00:52:11,000
That's because it's very high frequency.

1195
00:52:11,000 --> 00:52:16,000
And this means the dogs can hear the frequency, but we can't because it's still too high.

1196
00:52:16,000 --> 00:52:17,000
Hey, look at Rocky.

1197
00:52:19,000 --> 00:52:20,000
It's okay, boy.

1198
00:52:20,000 --> 00:52:23,000
Did you see Rocky's reaction to the electric toothbrush?

1199
00:52:23,000 --> 00:52:25,000
And toothbrushes are on the list.

1200
00:52:25,000 --> 00:52:26,000
Do you think?

1201
00:52:26,000 --> 00:52:27,000
Do you think?

1202
00:52:27,000 --> 00:52:30,000
Do I think that that tiny toothbrush could be the source of the problem?

1203
00:52:30,000 --> 00:52:32,000
Hey, it's a possibility.

1204
00:52:32,000 --> 00:52:35,000
Remember on the Matrix board, every subdivision had toothbrushes.

1205
00:52:35,000 --> 00:52:38,000
But Sal and Cecil doesn't have any dogs barking.

1206
00:52:38,000 --> 00:52:42,000
Well, maybe that subdivision didn't buy any toothbrushes from the salesman.

1207
00:52:42,000 --> 00:52:43,000
That must be it.

1208
00:52:43,000 --> 00:52:45,000
Hey, I think I see Mr. Big T outside.

1209
00:52:45,000 --> 00:52:47,000
Hey, let's go catch him.

1210
00:52:47,000 --> 00:52:48,000
Okay.

1211
00:52:49,000 --> 00:52:50,000
Excuse me, sir.

1212
00:52:50,000 --> 00:52:52,000
Yes, what? What do you want?

1213
00:52:52,000 --> 00:52:54,000
Are you the faulty toothbrush salesman?

1214
00:52:54,000 --> 00:52:57,000
I mean, are you selling the Gump Sonic Turbo Model toothbrush?

1215
00:52:57,000 --> 00:52:58,000
Excuse me, young man.

1216
00:52:58,000 --> 00:53:00,000
I sell only quality toothbrushes.

1217
00:53:00,000 --> 00:53:03,000
There's absolutely no proof that they're faulty.

1218
00:53:03,000 --> 00:53:05,000
Did you see his teeth?

1219
00:53:05,000 --> 00:53:07,000
I can tell he's not using his toothbrush.

1220
00:53:08,000 --> 00:53:09,000
Okay, sir.

1221
00:53:09,000 --> 00:53:12,000
But aren't you the salesman that sells toothbrushes door to door?

1222
00:53:12,000 --> 00:53:13,000
Yes, that's me.

1223
00:53:13,000 --> 00:53:14,000
Best toothbrushes on the market.

1224
00:53:14,000 --> 00:53:16,000
Can I interest you in one?

1225
00:53:16,000 --> 00:53:17,000
No, thank you.

1226
00:53:17,000 --> 00:53:20,000
But you could tell us which subdivision you sell those toothbrushes to.

1227
00:53:20,000 --> 00:53:22,000
Um, let me get my list.

1228
00:53:22,000 --> 00:53:23,000
Let me see.

1229
00:53:23,000 --> 00:53:29,000
I sold them in Sleeping Subdivision, Midnight Growl, and Cochlear Cascade.

1230
00:53:29,000 --> 00:53:32,000
Did you sell any to Sound Seaside?

1231
00:53:32,000 --> 00:53:34,000
No, my competition beat me to the punch.

1232
00:53:34,000 --> 00:53:35,000
This could be it.

1233
00:53:35,000 --> 00:53:38,000
Those three subdivisions are where most of the barking took place.

1234
00:53:38,000 --> 00:53:40,000
Let's go tell Dr. D.

1235
00:53:40,000 --> 00:53:41,000
Bye.

1236
00:53:41,000 --> 00:53:42,000
Bye.

1237
00:53:42,000 --> 00:53:43,000
Wait, wait, guys.

1238
00:53:43,000 --> 00:53:47,000
Don't you want to buy a Gump Sonic Turbo Best Toothbrush in town?

1239
00:53:48,000 --> 00:53:51,000
Well, I can't wait to tell Dr. D.

1240
00:53:51,000 --> 00:53:54,000
Dr. D., we have some really great news.

1241
00:53:54,000 --> 00:53:55,000
What's the news?

1242
00:53:55,000 --> 00:53:57,000
We figured out the problem of the dogs barking.

1243
00:53:57,000 --> 00:53:59,000
It's all because of this.

1244
00:54:01,000 --> 00:54:02,000
Listen to this.

1245
00:54:02,000 --> 00:54:04,000
The toothbrushes were malfunctioning,

1246
00:54:04,000 --> 00:54:07,000
so they are producing at the frequency that the dogs could hear.

1247
00:54:07,000 --> 00:54:10,000
We learned that high frequencies travel a short distance in a straight line.

1248
00:54:10,000 --> 00:54:14,000
When people were using the toothbrushes in the early morning or the late night,

1249
00:54:14,000 --> 00:54:16,000
the sound was making the dogs bark.

1250
00:54:16,000 --> 00:54:21,000
We also learned that the noises coming from the dogs inside traveled to the outside.

1251
00:54:21,000 --> 00:54:24,000
And this set off barking from the dogs outside.

1252
00:54:24,000 --> 00:54:25,000
This is great.

1253
00:54:25,000 --> 00:54:28,000
Again, we learned that the scientific method really worked.

1254
00:54:28,000 --> 00:54:31,000
We identified the problem of the barking dogs.

1255
00:54:31,000 --> 00:54:33,000
Dog owners sent their observations by e-mail.

1256
00:54:33,000 --> 00:54:36,000
We learned that there were dogs barking early in the morning and late in the evening.

1257
00:54:36,000 --> 00:54:40,000
We learned through our research that dogs could hear sounds humans couldn't.

1258
00:54:40,000 --> 00:54:43,000
We gathered information from our experts, the web, and our e-mails.

1259
00:54:44,000 --> 00:54:47,000
All these things helped us eliminate possibilities.

1260
00:54:47,000 --> 00:54:50,000
We learned through our research and experimentation

1261
00:54:50,000 --> 00:54:54,000
that it couldn't be the factory because high frequency sounds don't bend around corners easily

1262
00:54:54,000 --> 00:54:56,000
and couldn't make it across town.

1263
00:54:56,000 --> 00:54:59,000
So as we found out, our first hypothesis wasn't correct.

1264
00:54:59,000 --> 00:55:02,000
I like the way you questioned your first hypothesis.

1265
00:55:02,000 --> 00:55:05,000
We did more research and listened to KSNN

1266
00:55:05,000 --> 00:55:08,000
and found out when the dogs were brought inside, it only made things worse.

1267
00:55:08,000 --> 00:55:12,000
So with some smart thinking, we figured out it must be an inside sound.

1268
00:55:12,000 --> 00:55:14,000
We narrowed our search and looked at our data

1269
00:55:14,000 --> 00:55:17,000
and we found out that toothbrushes had to be the logical choice.

1270
00:55:17,000 --> 00:55:20,000
Of course, we did confirm it with Mr. T.

1271
00:55:20,000 --> 00:55:23,000
We sure won't ever forget his face.

1272
00:55:23,000 --> 00:55:25,000
You scientific method did a great job.

1273
00:55:25,000 --> 00:55:27,000
What do we say?

1274
00:55:27,000 --> 00:55:28,000
All we can say is this.

1275
00:55:28,000 --> 00:55:32,000
The Treehouse Detectives solved yet another case.

1276
00:55:36,000 --> 00:55:39,000
Wa-la, wa-la, wa-la.

1277
00:55:39,000 --> 00:55:41,000
Wa-la.

1278
00:55:42,000 --> 00:55:44,000
I can't fix myself.

1279
00:55:49,000 --> 00:55:52,000
I've got one strand that keeps on falling out of the top.

1280
00:55:52,000 --> 00:55:55,000
I can't explain it. I can't explain it. I can't explain it.

1281
00:56:12,000 --> 00:56:13,000
All right, all right.

1282
00:56:32,000 --> 00:56:33,000
All right, all right.