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The Case of the Barking Dogs

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Why? Files Video containing nine segments as described below. NASA Why? Files segment explaining how to form hypotheses, collect data, and build data matrices. NASA Why? Files segment explaining how bats use high-frequency sound to navigate. NASA Why

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Hey, you heard me, yeah, you come see our clubhouse and our tree. 00:00:00
We are kids on a mission to educate ourselves about the NASA vision. 00:00:18
Come explore math and science, cause that's what makes our alliance. 00:00:23
We are the WAPA club, we yearn to learn and want to see. 00:00:28
Everything that we can be, so come join us on our journey. 00:00:32
Don't you touch that dial, and welcome to the NASA WAPA house. 00:00:37
Wait, what are you doing? 00:00:44
Look, you just poured orange juice in your cereal. 00:00:46
I can't believe I just did this, and I'm so tired. 00:00:48
Hi, Jacob. 00:00:52
Hi. 00:00:53
Oh, wow, this is so cool. 00:00:54
Oh, this is my friend PJ, he's a friend from school. 00:00:56
I taught him about our tree house. 00:00:58
Hi. 00:01:00
Hey. 00:01:01
What are you guys doing in this place? 00:01:02
You'll find out soon enough. 00:01:03
I asked my two friends to join us. 00:01:04
This is Kaylee and Catherine. 00:01:06
Hi. 00:01:08
Pretty neat. 00:01:09
I like the slang. 00:01:10
You all won't believe what I just did. 00:01:12
What did you do? 00:01:14
I was so tired that I accidentally poured orange juice in my cereal. 00:01:15
My dog Rocky woke me up during the night. 00:01:20
Sometime around 1030. 00:01:24
So did my dog Arf. 00:01:26
He just started barking for some reason. 00:01:28
You have a dog named Arf? 00:01:30
Well, yeah, it makes sense. 00:01:32
You know, Arf, Arf. 00:01:34
Arf, Arf, Arf. 00:01:35
How long has this been going on? 00:01:37
For the last several nights. 00:01:38
Hey, KSNN is coming on. 00:01:40
Oh, cool. 00:01:43
And now, KSNN afternoon news. 00:01:45
Brought to you by the Gumsonic Turbo Electric Toothbrush. 00:01:48
Brush your teeth at supersonic speed with a Gumsonic Turbo. 00:01:52
Good afternoon. 00:01:56
I'm Ted Toombs. 00:01:57
Today's top story, barking dogs are keeping our city's residents awake. 00:01:58
Reports began to come in between 10 p.m. and midnight last night. 00:02:03
Our on-the-scene reporter, I Am Listening, is live with this report. 00:02:06
Thanks, Ted. 00:02:10
As you well know, dogs will bark at just about anything. 00:02:11
And they were certainly barking last night. 00:02:15
But no one here seems to know exactly why. 00:02:18
Some residents speculated that a cat or a prowler may have caused the dogs to bark. 00:02:21
Or it could have been something as simple as the wind. 00:02:26
We may never know. 00:02:29
I Am Listening, KSNN news on the scene. 00:02:31
Thanks, I Am, for that live report. 00:02:35
Authorities are pleading with local residents to bring their dogs in tonight 00:02:37
so that everyone can get some sleep. 00:02:41
I'm Ted Toombs, and that's all the news. 00:02:43
Wow, it's not just Rocky and Arf. 00:02:46
Dogs are barking in other areas of our neighborhood. 00:02:48
But what could be setting them off? 00:02:50
It could be a sneaky cat just trying to tease them. 00:02:52
Maybe the dogs are just talking to each other. 00:02:55
Right, at that hour? 00:02:57
I know we need to solve this problem. 00:02:59
Remember, we have that big test coming up next week? 00:03:01
I need my sleep. I can't afford another bad dream. 00:03:04
Today's Monday. Hopefully we can figure this one out by test time. 00:03:07
Maybe I can help you. I'm pretty good on the computer. 00:03:10
We could do a little research on the Internet. 00:03:13
Good idea. 00:03:15
I think we can help, too. 00:03:16
You know, six heads are better than one. 00:03:18
I can't believe I didn't make the connection. 00:03:20
You three are on KSNN. They called you the Treehouse Detectives. 00:03:22
That's us. 00:03:25
Maybe we could become Treehouse Detectives, too. 00:03:26
Hmm, maybe if we had a team of Treehouse Detectives, 00:03:29
we could figure out the problem of the barking dogs a lot faster. 00:03:32
My mom works on the team at National Lightning Research Center. 00:03:35
She says that they have a lot of success solving problems. 00:03:38
Maybe a team approach is the way to go. Let's go for it. 00:03:42
Okay. Let's get started. 00:03:45
We don't know much. 00:03:47
So far, all we know is that the dogs are barking and keeping everyone up. 00:03:49
We need help. Let's go ask our neighbor, Dr. D. 00:03:52
He helped us with the sink problem. 00:03:55
I have an idea. 00:03:57
Anytime we take a field trip, let's put it on the message board. 00:03:59
That way, all of us will know what's going on. 00:04:02
And any information you receive, just enter it into your computer. 00:04:04
Good idea. Maybe just the three of us should go before school. 00:04:07
I'll go to school early. 00:04:11
We will, too. 00:04:12
Let's go see Dr. D. 00:04:13
Okay. I'm sure he's working on one of his projects. 00:04:14
Hey, Dr. D. 00:04:22
I think he can hear you. You're so loud. 00:04:23
Hi, guys. What brings you over? 00:04:25
You look a little tired. 00:04:27
Some of us are very tired. We didn't get any sleep. 00:04:29
Both of our dogs were barking last night. 00:04:32
Dr. D., did Bernie bark last night? 00:04:35
Now you know Bernie. He's a little old. 00:04:38
It's time he's really out of it. 00:04:40
Did Bernie ever bark? 00:04:42
Oh, yeah. Sure. 00:04:43
Especially when he would smell or hear something he wasn't familiar with. 00:04:45
He'd start barking to scare it off. 00:04:48
So could there be a strange smell in the air that's making all of the dogs in the neighborhood start barking? 00:04:50
Could be. 00:04:55
I thought the three of us would be back working on another problem. 00:04:56
So I made up this board. 00:04:59
Oh, the scientific method. 00:05:01
I'll let you in on a little something. 00:05:04
The scientific method really helps you to solve problems. 00:05:06
Well, it helped us with the sink problem. 00:05:09
Remember, the scientific method is a step-by-step way to solve problems. 00:05:12
You can use it every day. 00:05:16
Oh, it's all coming back to me now. 00:05:18
I have something fun to show you that will help us review the scientific method. 00:05:20
Let's go to my lab and try it out. 00:05:24
Okay. 00:05:25
Does anyone know what this device is called? 00:05:30
I've seen one before, but I don't know what it's called. 00:05:32
Well, it's called a Newton's cradle. 00:05:34
If you wanted to find out how it worked, what would you do? 00:05:36
I guess I'd play around with it. 00:05:38
If we were following the scientific method, 00:05:40
then the first thing we would do is to identify the problem. 00:05:42
And, of course, we'd have to observe it. 00:05:45
Well, you're observing it already by playing with it. 00:05:47
What do you think we can say is the problem? 00:05:50
Well, I noticed that when I pull this ball back and then release it, 00:05:52
another ball pops out. 00:05:56
Does that happen every time? 00:05:57
And what about two balls? 00:06:00
That's the problem. 00:06:02
Remember, a problem has to be stated in the form of a question. 00:06:03
So our problem is, what happens to the balls on the other side 00:06:06
when I pull back a certain number of balls? 00:06:10
Isn't the next part of the scientific method research? 00:06:12
Yeah, that's correct. 00:06:14
Oh, I like this kind of research. 00:06:15
Let's see what happens when I pull back two balls. 00:06:17
I'll collect data. 00:06:20
Whoa, wait a minute. 00:06:21
Don't forget, we have to control the variables. 00:06:22
All the variables are the same except for one. 00:06:24
So pull back your two balls the same distance that Jacob pulled back his one. 00:06:27
That's right. I forgot about those variables. 00:06:31
Wait, what happens if I do three balls? 00:06:34
Are we ready for our hypothesis yet? 00:06:37
I know the hypothesis. 00:06:39
When you let go of two balls, two balls come out. 00:06:41
And if you let go of three balls, three balls come out. 00:06:43
That's right. 00:06:46
Remember, the hypothesis has to be written so it can be tested. 00:06:47
For example, the same number of balls I pull back will come out on the other side. 00:06:50
Okay, are we ready to experiment yet? 00:06:54
That's my favorite part. 00:06:56
Okay, let's test the hypothesis. 00:06:58
Let's see what happens. 00:07:00
If I pull back four balls, then four balls should come out on the other side. 00:07:01
Wow, our hypothesis was correct. 00:07:13
Congratulations. 00:07:16
But remember, the data does not support the hypothesis. 00:07:17
You have to try again. 00:07:20
But how do we observe for our problem of the barking dogs? 00:07:21
We can't stay up all night waiting for the dogs to start barking. 00:07:24
Well, we could. 00:07:27
Could? 00:07:29
Not me. 00:07:30
Remember, I have that big test next week. 00:07:31
I think we need to go back to the tree house to talk about this problem. 00:07:33
And then we need to decide what we want to research. 00:07:36
Thanks for all your help, Dr. Dean. 00:07:39
See you, Dr. Dean. 00:07:41
Bye-bye, guys. 00:07:42
Let's see. Remember our need-to-know board? 00:07:46
How could I forget that one? 00:07:48
Hey, it did help us solve the stink problem. 00:07:49
Okay, what do we know? 00:07:52
We know that dogs are barking at all hours of the night. 00:07:54
And we know that it's happening in our neighborhood. 00:07:56
We need to know what's making them bark. 00:07:58
Hmm, what would make a dog bark? 00:08:00
It could be a prowler or a robber staking out the area. 00:08:02
Or it could be just a mad cat getting evil. 00:08:05
Yeah, but if it was a prowler, wouldn't KSNN report about it? 00:08:08
Hmm, that's true. 00:08:11
And I haven't heard anything about prowlers or robbers on KSNN. 00:08:13
Cats aren't a new problem, but whatever's setting off the barking definitely is. 00:08:16
Well, remember what Dr. Dean told us about Bernie. 00:08:20
Bernie barks at strange smells or sounds. 00:08:22
KSNN didn't report any environmental problems with the smell. 00:08:25
Since Dr. Dean said it could also be sound, then let's investigate sound. 00:08:28
But remember the stink. It could be anything. 00:08:32
Yes, we need to find out a little more about sound. 00:08:35
We need to start our sound research. 00:08:38
We should also check out the NASA White Falls website. 00:08:40
I saw something about it on sound. 00:08:42
You will love the NASA White Falls website. 00:08:44
My mom's friend Ms. Leslie Bui works over at the Children's Museum. 00:08:47
Maybe she can help us with the sound problem. 00:08:51
I can't go over there right now. 00:08:53
I can't go either. 00:08:55
Okay, I'll put it in the computer. 00:08:56
Maybe one of the other treehouse detectives will show up. 00:08:58
This place is really neat. 00:09:09
Yeah, but I think we need to find Ms. Leslie Bui. 00:09:11
Hi, I'm Leslie Bui. I'm curator here at the Children's Museum of Virginia. 00:09:14
How can I help you? 00:09:17
Hi, some of our dogs are barking and are waking us up at night. 00:09:19
And we think that a really strange sound may be making them bark. 00:09:23
Can you tell us what sound is? 00:09:27
I think I can help you understand. Come over this way. 00:09:29
Sound is created by vibration. 00:09:36
A vibration is a back and forth motion a lot like this slinky. 00:09:38
An object vibrates and pushes air molecules around. 00:09:45
Then these set other air molecules into motion. 00:09:48
But we can't actually see the sound waves. 00:09:51
But I can help you see the vibrations. 00:09:54
This is a tuning fork. Listen. 00:09:56
I can hear a sound. 00:09:59
Me too. 00:10:02
And I can help you see the vibrations. 00:10:03
Vibration 00:10:07
What is frequency? 00:10:17
Frequency is the rate of vibration. 00:10:19
The higher the frequency, the higher the pitch. 00:10:21
Here, let me show you. 00:10:24
I've flattened a straw and cut points. 00:10:26
Now blow hard. 00:10:29
I'll cut the straw. 00:10:32
What do you notice? 00:10:38
It's higher. 00:10:39
I'll cut it again. 00:10:41
What changes? 00:10:43
It's even higher. 00:10:46
It's kind of like these tubes. 00:10:48
The longer the tube, the lower the sound. 00:10:50
That's right. The shorter the tube, the higher the pitch. 00:10:56
The shorter the tube, the higher the sound. 00:10:59
It's a lot like this straw. 00:11:02
Bianca, can you hear me? 00:11:05
Yes, Kaylee. We're having so much fun. 00:11:07
But now it's time to go. 00:11:10
I don't want to go. 00:11:12
But I'll go tell Mrs. Bowie thanks for the information. 00:11:14
Okay. See ya. 00:11:17
Bye. 00:11:19
Bye-bye. 00:11:20
Let's get back to work. 00:11:24
When my dog starts barking, I'm usually asleep. 00:11:25
Maybe we can ask other people to observe their dogs at night. 00:11:28
I'll call Kassadin and ask him to announce it on the news. 00:11:31
A big part of the scientific method is observation. 00:11:34
Remember what Dr. D said? 00:11:37
You have to define the problem through observation. 00:11:39
Observation is my favorite part of the scientific method. 00:11:41
If you want to learn more about the scientific method, 00:11:44
you should go to the NASA Wi-Fi's website. 00:11:46
Kassadin is great. 00:11:50
Look, we're already getting responses from different neighborhoods. 00:11:51
Let's see. 00:11:54
This person from Cochlea, Cascade, 00:11:55
says her dogs are barking early in the morning and late at night. 00:11:57
But in Midnight Growl, they say that they have barking mainly in the morning. 00:12:00
Let's email them back and see if they notice any funny smells, 00:12:04
sounds, or creatures around the house when the dogs were barking. 00:12:07
How are we going to sort all this data? 00:12:10
Data collection is also a big part of the scientific method. 00:12:12
With this data, we might be able to get to the bottom of this. 00:12:15
My mom told me about someone at NASA Langley 00:12:18
who spends a lot of time collecting and analyzing data. 00:12:21
Maybe we should talk to the experts at NASA. 00:12:24
Computer, get me an expert at NASA on analyzing and collecting data. 00:12:26
Hi, I'm Dr. Kara Lotterello at the NASA Langley Research Center. 00:12:33
Hi, we're trying to solve the problem of the barking dogs. 00:12:36
I might be able to help you. 00:12:39
We collect a lot of data here. 00:12:41
That's how we understand problems so we can solve them. 00:12:42
Right now, we're developing a flight simulation experiment 00:12:45
so we can test a new display idea. 00:12:48
We'll collect data from pilots to see if they can fly you 00:12:50
and your family around more safely with our new display, 00:12:53
as opposed to the old one. 00:12:55
We've received a lot of emails from neighborhoods. 00:12:57
We really need to know the best way to keep track of all this data. 00:12:59
How do you sort and collect your data? 00:13:02
Well, first we start with a question 00:13:04
or a statement of what we think is happening. 00:13:06
We call that statement a hypothesis. 00:13:08
So, for example, in my case, 00:13:10
I hypothesize that the new display will be better than the old display 00:13:12
and that that will be true for both younger and older pilots. 00:13:15
The data we collect will fill in the test matrix. 00:13:18
Each data point can be considered an observation. 00:13:20
In my experiment, I'm using the computer and sensors in the computer 00:13:23
to take these observations. 00:13:27
You can also take direct observations by looking at things yourself 00:13:29
or indirect observations by asking other people to report things to you. 00:13:32
How do we know if data is important to our problem? 00:13:36
Well, hopefully your data supports your hypothesis. 00:13:38
That means that the conditions you thought were important 00:13:41
actually did influence your measures. 00:13:43
If it doesn't, then you might want to collect some more data, 00:13:45
some different data, or rethink your hypothesis. 00:13:48
This is great. Remember the matrix Dr. D showed us in the stink problem? 00:13:51
We can use that to help us rule out some of the possible sources of the problem. 00:13:55
But how do we set up a matrix? 00:13:59
You really should set up your test matrix ahead of time, 00:14:01
before you collect data. 00:14:03
In my experiment, it's pretty simple, since I only have two factors of interest, 00:14:05
the display type and the age of the pilots. 00:14:08
And I have two levels for each of these factors. 00:14:11
For the display type, I have a new display and an old display. 00:14:13
And for the age of the pilots, I have younger and older pilots. 00:14:16
Your matrix helps you organize your data, 00:14:19
so you can look at it, analyze it, and understand what's important about your problem. 00:14:21
We can look at the data and get an idea about the source. 00:14:25
Thanks a lot for all your help. 00:14:28
Now we might be able to actually make some sense of all this. 00:14:30
Thanks for stopping by. Good luck. 00:14:33
Wow, we have more emails. 00:14:35
Maybe we will see a pattern in the increase of strange smells, sounds, or even prowlers. 00:14:37
Look, this person from Cochlear Cascade 00:14:42
says she didn't notice any strange smells when her dog started barking. 00:14:44
Smells seems like such a stretch. 00:14:47
I don't think we're going to solve this problem any time today. 00:14:49
I agree. Tonight, try to see what's going on when your dog starts barking. 00:14:52
I'll try. Let's all try. We need to figure this one out quick. 00:14:55
So what's up? Will the dogs continue to bark? 00:15:00
Are the treehouse detectives asking the right questions? 00:15:03
Will the scientific method work to solve the problem? 00:15:06
Tune in next time for The Case of the Barking Dogs. 00:15:09
We can use our information to plot exactly where the dogs are barking and possible causes. 00:15:15
Let's use black pushpins for dogs barking in the night, 00:15:21
blue ones for dogs barking in the day, 00:15:24
green for prowlers, 00:15:26
yellow for loud sounds, 00:15:28
and red ones for strange smells. 00:15:30
We have too many emails but not enough pushpins. 00:15:32
Remember in school, we used pictographs to represent large numbers. 00:15:34
Yeah, each pushpin can equal five barking dogs. 00:15:38
In Midnight Growl, we have 10 dogs barking in the day. 00:15:41
So I'll put two blue pushpins. 00:15:44
In Cochlear Cascade, we have 20 dogs barking in the day and 10 dogs barking at night. 00:15:48
That means we have four blue pushpins and two black ones. 00:15:53
Let's just put in a green pushpin for each neighborhood that reported prowlers. 00:15:57
That would be Midnight Growl and Sleepless Subdivision. 00:16:01
Hmm, if prowlers are the smallest, 00:16:05
Hmm, if prowlers are the source of the problem, 00:16:09
then wouldn't each neighborhood that reported barking dogs have prowlers? 00:16:12
And those with prowlers would have barking. 00:16:15
But by looking at the map, we can see this isn't true. 00:16:17
So I guess prowlers aren't causing the problem. 00:16:19
What about smells? 00:16:21
So far, no one has reported any bad smells. 00:16:23
And if it was a bad smell, wouldn't KSNN say something about it? 00:16:25
Good point. What about sound? 00:16:29
In Midnight Growl, we have dogs barking and some residents are noticing loud noises. 00:16:31
I'll put a yellow pushpin in Midnight Growl. 00:16:36
In Cochlear Cascade, there are dogs barking and they notice loud sounds. 00:16:39
Another pushpin for that neighborhood. 00:16:44
This looks promising. 00:16:46
In the email from Sound and Seaside, they've noticed loud sounds. 00:16:48
Let me get this one. 00:16:51
But there are no dogs barking. 00:16:53
So does this mean there's no connection to sound? 00:16:55
My guess is no. 00:16:58
We might want to research sound a lot more 00:16:59
because both Midnight Growl and Cochlear Cascade have barking dogs and sound. 00:17:02
There may be a connection. 00:17:07
You would think that all dogs would start barking at all loud sounds. 00:17:09
I think so far it's sound. 00:17:12
The map really helps us see it. 00:17:14
It sure has helped us to solve the problem. 00:17:16
You know, at the NASA White Falls website, there are some great activities using a map and a matrix. 00:17:18
You should check it out. 00:17:23
I think we need to concentrate on sound a little more. 00:17:24
Let's go back to our neat snowboard. 00:17:26
We know dogs are barking. 00:17:33
And we know that vibrations produce sound and that sound travels in waves. 00:17:35
We need to know more about how sound travels and how we hear it. 00:17:39
Let's think about sounds that make dogs bark. 00:17:44
Garbage trucks. 00:17:47
Sirens. 00:17:48
Stephenoids. 00:17:49
And work trucks. 00:17:50
I wonder if there's a reason why the dogs aren't hearing the sound in Sound and Seaside. 00:17:51
Maybe they have wax in their ears. 00:17:55
Yeah, right. 00:17:56
Maybe something's blocking the sound. 00:17:58
Maybe a wall keeping it from going to other parts of the sound. 00:18:00
That's a good idea. 00:18:02
Like what? 00:18:03
Maybe a wall. 00:18:05
Maybe more dogs are kept inside in that neighborhood. 00:18:06
That could be it. 00:18:08
I think there's more connections between barking dogs and sound than there is with prowlers or even smells. 00:18:10
I say we concentrate on sound. 00:18:16
My mom's friend knows a lot about ears. 00:18:18
I think she's called an audiologist. 00:18:20
Can you go visit her? 00:18:22
I can't. I have to do my homework. 00:18:24
Jacob and I will go. 00:18:26
Her name is Ms. Helen Denny. 00:18:27
She works at Sentara Hampton General Hospital. 00:18:29
She says we can come over anytime. 00:18:31
I'll email our parents and tell them where we're going. 00:18:33
Great. Let's get up and go. 00:18:35
Okay. 00:18:36
We're known as the Treehouse Detectives. 00:18:43
Oh. 00:18:45
We're trying to get some sleep, but the neighborhood dogs are keeping us up. 00:18:46
Who knew? 00:18:48
We wanted to know how our ears work. 00:18:49
That way we can figure out why the dogs keep barking. 00:18:51
And how sound travels. 00:18:53
If we know how sound travels, that might help us solve the problem. 00:18:55
I think I can help you out. 00:18:57
Let's move into the other room. 00:18:59
Cool. 00:19:00
What is all this stuff? 00:19:02
This is equipment we use to test people's hearing. 00:19:03
Can you tell us how our ears work? 00:19:05
Sure. 00:19:07
The outer ear collects and concentrates the sound energy. 00:19:08
Then this is channeled down the ear canal, and the eardrum vibrates, 00:19:10
and so do the small bones within the ear. 00:19:14
Then the sounds go through the cochlea, the hair cells bend, 00:19:16
and then the impulses are sent up the auditory nerve into the brain, 00:19:20
where they're decoded. 00:19:23
Other sounds people can't hear? 00:19:24
Sure, if they're above a certain frequency. 00:19:26
The human ear can hear frequencies between 20 and 20,000 vibrations a second. 00:19:28
Frequencies. 00:19:33
Hmm, that might be a clue. 00:19:34
Thanks for all your help. 00:19:36
Sure. 00:19:37
Bye. 00:19:38
Bye, and good luck. 00:19:39
Thanks. 00:19:40
I bet NASA Langley Research Center could help us. 00:19:42
My neighbor researches noise pollution and how it affects us. 00:19:44
I've heard of air pollution, but noise pollution? 00:19:47
Yes. 00:19:49
Her name is Ms. Brenda Sullivan. 00:19:50
Let's go over and talk to her. 00:19:52
Okay, I'll call my mom for a ride. 00:19:54
I'm sure glad it's a half day so we can get all this research done. 00:19:56
Yeah. 00:19:59
Too bad PJ couldn't make it. 00:20:01
What or who is that? 00:20:04
Oh, that's Fred DeHank. 00:20:06
You must be the treehouse detectives. 00:20:07
I'm Bianca, and this is Jacob. 00:20:09
We're trying to solve a really big problem. 00:20:11
Dogs are barking and keeping us up at night and in the early morning. 00:20:13
I heard about that in the news. 00:20:17
We think that a really loud sound might be making them bark. 00:20:18
We're researching sound. 00:20:22
We'd like to learn how you deal with sound problems. 00:20:23
Well, I'm a psychoacoustician here at NASA Langley Research Center. 00:20:26
That's a really big word. 00:20:30
I don't think I can even say that. 00:20:31
So what do you do here? 00:20:33
Well, as a psychoacoustician, I design, conduct, and analyze tests 00:20:35
that investigate the psychological effects of noise on people. 00:20:39
Let me show you one of my labs. 00:20:43
Is this a real plane? 00:20:46
No, this is a fake. 00:20:47
But we go up in real planes, we make recordings, 00:20:49
we bring them down to the lab, and we modify them. 00:20:51
Then we can play them back to people in here 00:20:54
and find out which kind of sounds they prefer. 00:20:56
So what kind of sounds do people prefer? 00:20:58
Well, quiet ones, really. 00:21:00
We hear from 20 vibrations per second to 20,000 vibrations per second, 00:21:02
and the low-frequency ones bother us less than the high frequencies. 00:21:07
For instance, have you heard a piece of chalk scratching on a chalkboard? 00:21:11
Yuck. 00:21:15
Well, that's a high-frequency sound. 00:21:16
What about dogs? Do they hear differently from us? 00:21:17
Well, I'm not an expert on dogs, 00:21:20
but I know dogs can hear higher frequencies than we do. 00:21:22
They can hear very high frequencies. 00:21:24
Come on, let's go. 00:21:26
So, we need to find out what kind of things make very high-frequency noises. 00:21:31
What about machines or factories? 00:21:36
They both might be possibilities. 00:21:38
That could be it. It could be a noise from a nearby factory. 00:21:39
We might have the answer. 00:21:42
You mean the hypothesis. 00:21:44
You need to go and talk to my friend, the veterinarian. 00:21:46
His name's Dr. Gooding. 00:21:48
Oh, here he is. He's right around the corner. 00:21:50
Great. I love going to pet hospitals. 00:21:52
I'll call my parents and see if it's okay. 00:21:55
I wonder what kind of neat pets we will see today. 00:21:58
Hi, we're the Treehouse Detectives. We're here to see Dr. Gooding. 00:22:00
Please come this way. How can I help you? 00:22:03
Thanks for helping us. 00:22:11
I'm Jacob, and this is Bianca. 00:22:12
Have you heard about the dog barking problem on KSNN? 00:22:14
Yes, I have. 00:22:17
I know it's keeping a lot of people up at night. 00:22:18
Tell me about it. 00:22:20
We need to know dogs hear sounds differently from us. 00:22:22
Whoa! Look at that big dog. 00:22:26
I know he can hear us. 00:22:28
Yes, dogs tend to hear at a much higher frequency than human beings. 00:22:31
This means they can hear sounds that the human ear cannot hear. 00:22:35
Dogs can hear sounds between 67 Hz and 45 kHz. 00:22:39
Now, people can only hear between 20 Hz and 20 kHz. 00:22:43
Do the insides of dogs' ears look like ours? 00:22:48
What? 00:22:50
That's actually a good question. 00:22:51
I have something to show you. Let's go, guys. 00:22:53
Let's take a look at Millie's ears. 00:22:59
Actually, the anatomy of the human ear is similar to that of the dog. 00:23:02
Those are actual pictures of Millie's ears. 00:23:06
However, dogs have some equipment or parts that might have better hearing. 00:23:10
For example, dogs tend to have a long ear canal that might allow sound to be funneled or directed into the hearing apparatus. 00:23:14
It's a lot like this funnel, something that is used to direct water into this bottle so that you don't spill it. 00:23:22
So, that's why dogs can hear noises at higher frequencies. 00:23:31
They can hear things that we can't. 00:23:35
That's true. Dogs used to be wild before they were domesticated. 00:23:38
They had to survive by finding food and escaping predators. 00:23:42
Therefore, they might have had to depend on their ears to survive. 00:23:46
That's cool. 00:23:50
Dr. Gooding, do you know any good examples of dogs that can hear? 00:23:51
Hmm, let's see. 00:23:55
Are you familiar with dog whistles or pest zappers? 00:23:56
These are good examples of high-frequency sounds. 00:24:00
Thanks, doctor, for all your information. 00:24:03
We'll see you later. 00:24:05
Goodbye. 00:24:06
Bye. 00:24:07
I wonder if more people have bought dog whistles lately. 00:24:09
We should check that out. 00:24:12
Hey, guys, there's a cool activity at the NASA Wi-Fi's website where it lets you build your own dog whistle. 00:24:13
It's called Dog Whistle. 00:24:18
We should check that out. 00:24:20
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. 00:24:21
You should check it out. 00:24:27
We interrupt this broadcast for a special Kid Science News Network bulletin. 00:24:32
We go now live to reporter I Am Listening. 00:24:36
Thanks, Ted. There's nothing new to report on the barking dog dilemma. 00:24:39
The mystery has not been solved. 00:24:44
I repeat, the mystery has not been solved. 00:24:47
Many people continue to suffer from lack of sleep as the dogs continue to bark between 10 p.m. and midnight every night. 00:24:51
I'm I Am Listening, KSNN News. 00:25:00
Back to you, Ted. 00:25:03
Thanks for that informative report, I Am. 00:25:05
What? This just in, Gumsonic, manufacturer of the most popular electric toothbrushes on the market, 00:25:08
announced today that there may be problems with their newest model, the Gumsonic Turbo. 00:25:14
Gumsonic stressed that there is no threat to the general population and more studies are being conducted. 00:25:19
More after this. 00:25:25
We need to learn more about very high frequency sounds because that is what the veterinarians said dogs can hear and we can't. 00:25:27
So we need to find out what kinds of things make high frequency noises. 00:25:33
Hmm, Ms. Sullivan says it could be the factory and Dr. Gooding says it could be pest zappers or dog whistles. 00:25:37
I think they're all possibilities. 00:25:44
I think the factory is it. Yes, we might have the answer. 00:25:46
You mean a hypothesis. 00:25:49
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. 00:25:51
Look, we have an email from Dr. D. 00:25:57
He wants to take us to NASA. He's going to meet us outside. 00:26:00
I talked to Brenda Sullivan. She's allowing us to use the anechoic chamber. 00:26:04
The what? Just follow me. 00:26:07
What do you think of this? 00:26:12
Wow, this is pretty amazing. 00:26:14
An anechoic chamber is a special chamber that absorbs sounds. 00:26:16
Sounds can't bounce off the walls, the ceiling or the floor. 00:26:19
This is weird. What are all those things on the wall? 00:26:22
They're wedge-shaped sponges. That's what absorbs the sound. 00:26:25
Let's try an experiment. 00:26:28
Bianca, stand over here. Matthew, go across the room from her. 00:26:30
Okay. 00:26:33
Now face into the wall, Bianca, and yell as loud as you can. Go ahead. 00:26:34
Wow! 00:26:38
What did you hear? 00:26:40
I could hear, but she wasn't that loud. 00:26:41
I yelled as loud as I could, and you still couldn't hear me? 00:26:43
Not really, and that's unusual for once. 00:26:46
Let me show you another property of sound. 00:26:51
Now, Matthew, stand about a half a meter away from the speaker. 00:26:53
Now, after I turn up the sound really loud, 00:26:57
I want you to walk backwards until the sound appears to be about half as loud. 00:26:59
Okay. 00:27:03
Ready? 00:27:04
It sounds about half as loud here. 00:27:10
It's not surprising to find out that sound gets softer as you move further away from the source. 00:27:12
This is called an inverse relation. 00:27:16
Mathematics will help us understand how it works. 00:27:18
Every time you move a little more than three times further away, 00:27:21
it will sound half as loud. 00:27:25
I have so much information in my head, it hurts. 00:27:28
We need to go back to the treehouse and sort it all out if we need to know more. 00:27:31
Let's go. 00:27:35
Dr. D says that we need to look for loud sounds that could be causing the dogs to bark. 00:27:37
I know one sound that's really loud. 00:27:42
It's a garbage truck, and I know they make dogs bark. 00:27:44
What about sirens? 00:27:46
My dog always barks when he hears a siren. 00:27:47
Yeah, and there's a new factory near a hollow sound. 00:27:50
I bet that's it. 00:27:52
You know, and the stink it was, the candy factory. 00:27:54
Maybe noises from the factory are making the dogs bark. 00:27:56
That should be our hypothesis. 00:27:59
Let's look at these emails. 00:28:01
Wow, lots of dogs are barking in hollow sound. 00:28:03
That's right near the factory. 00:28:05
So that's got to be it. 00:28:07
Oh, this is too easy. 00:28:09
We are so good. 00:28:11
So what's up? 00:28:13
Will the treehouse detectives solve this problem? 00:28:14
Do you think their hypothesis is right or wrong? 00:28:16
Are high and low frequencies an important part of solving this problem? 00:28:19
We'll see you next time for the next NASA Wi-Files, 00:28:22
The Case of the Barking Dog. 00:28:25
Did you watch your dog last night? 00:28:31
I tried to, but I've been so tired, I fell right asleep. 00:28:33
Did you ever hear that sound connectivity Matthew was talking about? 00:28:36
I did. It was a lot of fun. 00:28:39
But I couldn't hear the high frequency noise like that of a dog whistle. 00:28:41
I don't think it'll help us solve the problem. 00:28:44
Oh, well, at least we tried. 00:28:46
But I think we're getting somewhere. Let's get organized. 00:28:48
Why do we need to do that? 00:28:51
We already know what's causing the problem. 00:28:52
It's the factory. 00:28:54
Dr. D told us not to jump to any conclusions. 00:28:55
So let's figure this thing out. 00:28:58
Back to the matrix board. 00:29:00
Across the top are the names of the neighborhoods. 00:29:05
Midnight Growl, 00:29:08
Cochlear Cascade, 00:29:09
Sound Seaside, 00:29:11
and Southern Sleepless Subdivision. 00:29:12
Down the left side, we have one cause, 00:29:14
which is garbage pickup. 00:29:17
And we have the effect of dogs barking. 00:29:18
The trucks were in Midnight Growl on Monday, 00:29:21
and there were dogs barking. 00:29:23
Then, in Sleepless Subdivision, 00:29:25
they were there on Tuesday, 00:29:27
but no dogs were barking. 00:29:28
Okay, in Sound Seaside, they have not yet had garbage pickup. 00:29:30
In Cochlear Cascade, 00:29:34
there was garbage pickup on Wednesday, 00:29:35
and the dogs were still barking. 00:29:37
This is confusing. 00:29:39
The matrix shows us that there is a relationship 00:29:40
between garbage pickup and dogs barking, 00:29:43
but only on two days. 00:29:45
Cochlear Cascade had parking on Monday, 00:29:47
but there was no garbage pickup on that day. 00:29:49
Yeah, and let's remember, 00:29:51
dogs have been barking at night, 00:29:52
and there's no garbage pickup at night. 00:29:54
Maybe we need to rule out garbage trucks. 00:29:56
What about sirens? 00:29:58
Forget it. 00:29:59
Sirens go off all the time, 00:30:00
so why would it be more barking now than before? 00:30:01
I think we need to find a new hypothesis. 00:30:04
Good morning, I am Ted Toon 00:30:11
with the Kids Science News Network News. 00:30:14
The mystery of the barking dogs 00:30:17
continues to confuse authorities. 00:30:18
More dogs were heard barking last night, 00:30:20
and even more people were kept awake 00:30:22
between 10 p.m. and midnight. 00:30:24
We urge you to please bring in those dogs 00:30:26
so that those of us who have to get up in the morning 00:30:29
can get some sleep! 00:30:31
And in consumer news, 00:30:37
the Gum Sonic Company, 00:30:38
makers of the Gum Sonic Turbo, 00:30:39
issued an official product recall today. 00:30:41
Anyone who bought the Gum Sonic Turbo 00:30:44
model electric toothbrush 00:30:46
is urged to return it 00:30:47
to the Gum Sonic Company 00:30:49
for a full refund. 00:30:52
And that's all the news. 00:30:54
I really think we're onto something, 00:31:00
but we need to figure out 00:31:01
where the sound could be coming from. 00:31:02
That's a good idea, 00:31:04
because right now, 00:31:05
we don't know if the sound is coming from outside, 00:31:06
inside our houses, 00:31:08
or even from across town. 00:31:09
Maybe we need to know more about 00:31:11
how fast sound can travel. 00:31:12
Let's experiment. 00:31:13
That's part of the scientific method. 00:31:14
Yeah, maybe our teacher and friends at school can help us. 00:31:16
I'll email my teacher 00:31:18
and ask her if she has any experiments 00:31:19
to help us see how fast sound travels. 00:31:21
Okay. 00:31:23
Good morning, Mrs. Rickles. 00:31:27
Well, good morning. 00:31:29
I've got your email this morning, 00:31:30
and I have just the experiment for you. 00:31:31
I have it all written down here. 00:31:33
Here you go. 00:31:34
Thanks, Mrs. Rickles, for helping us. 00:31:35
You're welcome. 00:31:37
It looks like we need to go outside 00:31:38
and create echoes. 00:31:39
And measure how long it takes us to hear those echoes. 00:31:40
Let's get started. 00:31:43
Okay. 00:31:44
Okay, everybody line up in threes. 00:31:46
One person will do the clapping, 00:31:48
the other person will time the number of claps, 00:31:50
and the other will take the data. 00:31:52
We need a set of pipes, 00:31:54
a meter stick, 00:31:56
a stopwatch, 00:31:57
a pencil and a paper, 00:31:58
and goggles. 00:31:59
We will use the side of the building 00:32:00
to bounce sound off 00:32:02
to create an echo. 00:32:03
Measure 57 meters from that wall. 00:32:04
I can do that, 00:32:07
but I need help. 00:32:08
Help! 00:32:09
Okay, you need to stand right here. 00:32:14
This is where we'll start the experiment. 00:32:16
You need to start clapping these two items together like this 00:32:18
and listen for the echo. 00:32:22
You really need to get a rhythm going 00:32:24
so that you can hear the echo in between claps like this. 00:32:25
Let's try it. 00:32:30
That's good. 00:32:32
Okay, I'm hearing the echo. 00:32:34
Let's time the number of claps in 20 seconds 00:32:35
and measure how long it takes us to hear that echo. 00:32:38
Let's time the number of claps in 20 seconds 00:32:41
and record our data 00:32:43
so we can analyze it when we get back inside. 00:32:44
I have 30 claps. 00:32:50
That's great! 00:32:51
Let's do the experiment again 00:32:52
so we can take an average of the number of claps. 00:32:53
Remember, when you are experimenting, 00:32:56
you must have repeated trials. 00:32:58
In the stink problem, 00:33:00
we learned that we need to perform the experiment 00:33:01
at least three times. 00:33:03
Okay, we need another group to line up. 00:33:05
Let's count down. 00:33:08
Three... 00:33:09
Two... 00:33:10
One... 00:33:11
Go! 00:33:12
Do you know why it's important to take an average? 00:33:27
Taking an average helps us to eliminate the possibility 00:33:29
that someone counted wrong, 00:33:32
read the stopwatch wrong, 00:33:34
or didn't understand the instructions. 00:33:36
Do you know how to calculate an average? 00:33:39
It's easy. 00:33:41
For example, you can take the numbers 20, 22, and 19. 00:33:42
You add them up and divide them by 3, 00:33:46
and that's your average. 00:33:48
Now to calculate the speed of sound, 00:33:50
we need to take the number of seconds 00:33:52
and we need to divide it by the number of claps. 00:33:54
This is going to tell us the amount of time between claps. 00:33:57
What do we get? 00:34:00
That's 0.66. 00:34:02
Let's see. 00:34:04
I calculate that to be two-thirds of a second between claps. 00:34:05
Okay, we have two-thirds of a second between claps, 00:34:10
and the echo comes halfway between claps. 00:34:14
Then it only takes one-third of a second 00:34:17
for the sound to travel to the wall and back to us. 00:34:19
I guess that sounds correct. 00:34:22
And to figure out how far it travels 00:34:24
from us to the wall and back, 00:34:26
wouldn't we just take 57 meters and double it? 00:34:28
What? 114 meters? 00:34:31
Correct. 00:34:34
Now to figure out the speed, 00:34:35
divide distance traveled by the time. 00:34:37
Okay, that would be 114 meters 00:34:39
divided by one-third of a second. 00:34:42
That comes to 342 meters per second. 00:34:44
That's beyond fast. 00:34:47
A meter is just a little longer than a yard. 00:34:50
This means that sound travels 00:34:52
more than three football fields in a second. 00:34:54
Wow, that's really fast. 00:34:56
Now we actually saw how fast sound travels. 00:34:59
Let's go tell Dr. D. 00:35:02
Hey, Dr. D. 00:35:04
Oh, hi, kids. 00:35:06
Dr. D, I did this really cool experiment at school, 00:35:08
and it showed that sound traveled so fast. 00:35:11
What do you think affects how fast sound travels? 00:35:14
Oh, you mean, what are the variables? 00:35:16
Ah, very good. 00:35:19
Could it have anything to do with the temperature? 00:35:20
That's a great question. 00:35:22
The speed of sound increases with temperature. 00:35:23
That's one variable. 00:35:25
Another variable is the moisture. 00:35:26
I guess this means that on hot, humid days, 00:35:28
when it's really sticky outside, 00:35:30
the sound travels really fast. 00:35:32
No, not that much faster. 00:35:34
The material that sound travels through, 00:35:35
which we call the medium, makes a big difference. 00:35:37
Generally, sounds travel faster through liquids 00:35:39
than they do through air. 00:35:42
They travel faster through solids than through liquids. 00:35:43
Why does that happen? 00:35:45
It's called elasticity. 00:35:47
I'll show you how it works. 00:35:48
I'm doing an experiment. 00:35:49
Matthew, why don't you finish 00:35:50
lining up the dominoes on the table, 00:35:51
if you would, please. 00:35:53
Sure. 00:35:54
Bianca, grab ahold of this spring 00:35:57
and hold on really tight. 00:35:59
I'm going to send a wave pulse down the spring. 00:36:01
Pay careful attention to how fast it's going. 00:36:04
All right. 00:36:08
Now, solids and liquids are more elastic than gases. 00:36:09
See how much of a difference this makes? 00:36:13
I'm going to increase the elasticity of this spring 00:36:15
by increasing its tension. 00:36:18
Elasticity tells me how fast 00:36:19
things are brought back into place 00:36:21
when they're disturbed. 00:36:23
Are you ready? 00:36:24
Watch carefully. 00:36:25
Wow, it's really moving. 00:36:29
Notice how the wave, or energy, 00:36:31
travels through the spring, 00:36:33
but the spring doesn't go anywhere. 00:36:34
It just vibrates in place. 00:36:35
It's like the dominoes that Matthew just set up. 00:36:37
When he knocks over the first one, 00:36:39
the energy will travel through, 00:36:41
but the individual dominoes just move a little bit. 00:36:43
Try it, Matthew. 00:36:46
Okay. 00:36:47
Cool. 00:36:54
Now we know that sound gets softer 00:36:55
as it travels away from a source. 00:36:56
When sound travels from medium, 00:36:57
the molecules vibrate in place, 00:36:59
but don't really go anywhere. 00:37:01
What else do we know about sound? 00:37:02
Well, we know the medium affects how fast sound travels. 00:37:04
We also know it influences how far sound goes. 00:37:07
But I thought we already talked about 00:37:10
how sound died off in the distance 00:37:11
when we were in that room with all the sponges. 00:37:13
Well, that's right. 00:37:15
We discussed how sound gets softer with distance 00:37:16
because the waves spread out. 00:37:18
Is that like when you throw a rock into a pond of water 00:37:20
and the circles get bigger as they move away from the splash? 00:37:23
Exactly. 00:37:26
But in addition to that, 00:37:27
the medium affects how far sound travels 00:37:28
by absorbing the sound energy. 00:37:30
I have a friend over at NASA who specializes in acoustics. 00:37:32
Her name is Dr. Christine Darden. 00:37:35
You should go talk with her. 00:37:37
She can help you to understand 00:37:38
how the medium affects how far sound travels. 00:37:39
Maybe we can dial her up when we get back to the treehouse. 00:37:42
Thanks for all your help, Dr. D. 00:37:45
See you. 00:37:47
Bye. 00:37:48
Bye, guys. 00:37:49
Computer, get us Dr. Christine Darden 00:37:51
at NASA Langley Research Center. 00:37:53
Oh. 00:37:58
Hi, kids. 00:37:59
I'm Dr. Darden, 00:38:00
an engineer here at NASA Langley Research Center. 00:38:01
I've done sonic boom research here for many, many years. 00:38:04
What's a sonic boom? 00:38:07
Doesn't it have to do with the speed of airplanes? 00:38:09
Yes, it does. 00:38:12
A sonic boom occurs when an airplane 00:38:13
travels faster than the speed of sound. 00:38:15
We do lots of sonic boom testing in this wind tunnel. 00:38:18
In fact, the first models that we used 00:38:22
were no larger than my fingernail. 00:38:24
When an airplane travels through the air, 00:38:27
it generates pressure waves that travel 00:38:29
at the speed of sound in all directions. 00:38:31
A plane flying at the speed of sound 00:38:34
moves at the same speed as the disturbances, 00:38:36
causing a shock wave to form. 00:38:39
When the plane flies faster than the speed of sound, 00:38:41
this shock wave forms a cone shape 00:38:44
attached to the nose of the airplane. 00:38:47
Air pressure just inside the cone is high, 00:38:49
and air pressure ahead of the cone is normal. 00:38:52
This shock wave, or cone, extends to the ground, 00:38:55
perhaps 10 to 15 miles. 00:38:58
The sonic boom is heard when the sudden change in pressure 00:39:01
crosses your ear. 00:39:04
Let me demonstrate for you with this balloon. 00:39:06
The air pressure inside this balloon 00:39:09
is higher than the air pressure outside the balloon. 00:39:11
If I pop the balloon, 00:39:14
a shock wave is generated much like a sonic boom. 00:39:15
Could there be a very high-frequency sound 00:39:18
that people can't hear but dogs can? 00:39:20
Absolutely, but remember, 00:39:22
that very high-frequency sound can't come from far away. 00:39:24
Because high-frequency sounds don't travel very far. 00:39:27
That's right. 00:39:30
Thanks, Dr. Darden. 00:39:31
You're welcome. 00:39:33
Goodbye, and good luck. 00:39:34
Well, we have already eliminated garbage trucks and sirens 00:39:36
and most other loud noises. 00:39:41
The factory is still a possibility. 00:39:43
But people haven't come playing yet, 00:39:45
so it must be a very high-frequency sound. 00:39:47
And besides, very high-frequency sounds can't travel very far, 00:39:49
so it can't be the factory. 00:39:53
So I guess our hypothesis of the factory is wrong. 00:39:55
It's back to the drawing board. 00:39:57
Maybe we need to find something close to our houses 00:39:59
or even inside our houses that make a high-frequency noise. 00:40:01
How are we supposed to do that? 00:40:04
We can't even hear high-frequency noises. 00:40:05
Remember those dog whistles? 00:40:07
They are high-frequency. 00:40:09
Yes. 00:40:10
Let's check that out. 00:40:11
Let's check that out tomorrow. 00:40:12
Sounds good to me. 00:40:13
So what's up? 00:40:15
Do you think dog whistles are the source of the problem? 00:40:16
Are the dogs hearing a sound from inside their house, 00:40:19
or could there be an outside source for this problem? 00:40:21
Don't miss the final episode of the NASA Y-Files, 00:40:24
The Case of the Barking Dogs. 00:40:27
Okay, thank you. 00:40:34
Bye-bye. 00:40:35
Well, that's it. 00:40:37
I called the last pet store. 00:40:38
Most of them said they haven't sold any dog whistles recently, 00:40:40
and some of them said they never even carry dog whistles. 00:40:43
Great! 00:40:46
This means we can cross off high-frequency sound as a hypothesis. 00:40:47
No, it means we can cross off dog whistles. 00:40:50
Have you figured out the answer yet? 00:40:53
We could use your help. 00:40:55
This is really hard. 00:40:56
We're never going to figure out why the dogs are barking, 00:40:57
and I'm never going to get any sleep. 00:40:59
Okay, let's think. 00:41:02
We've learned a lot, but we still don't know what the answer is. 00:41:03
It could be an inside noise, 00:41:06
or, let me think, a coffee grinder or blender? 00:41:08
Yeah, even my mom's blender makes a lot of noise. 00:41:12
No, I don't think it could be a coffee grinder or blender, 00:41:15
because they've been around for a long time. 00:41:17
This is so hard. 00:41:19
Remember what Dr. D says, 00:41:21
never give up, because the answer could be right in front of us. 00:41:23
Really, all I see in front of me is Jacob. 00:41:26
Okay, you guys, knock it off. 00:41:29
We need to get back to our neat snowboard. 00:41:31
We now know it's not dog whistles. 00:41:35
But it's strange, because both the dogs inside and outside are barking. 00:41:37
It still could be a high-frequency sound. 00:41:41
But high-frequency sounds don't travel very far. 00:41:43
We also know that sounds can travel through a solid liquid nanogas. 00:41:46
So we need to know which things make high-frequency sounds. 00:41:50
Who should we ask? 00:41:53
Let's do an Internet search. 00:41:55
More research. 00:41:56
Yes, but this research is fun. 00:41:58
Look at these animals that use high frequencies. 00:42:02
Bats, dolphins, that's interesting. 00:42:04
Hey, we're learning about bats in school. 00:42:07
Maybe we could go to a museum. 00:42:09
I think I'll stay here and look at this research. 00:42:11
I'll stay with you. 00:42:13
Okay, I'll get one of the other treehouse detectives to come with me. 00:42:14
You do look like you're looking for something. 00:42:25
My name is Mrs. Chris Lewis. Can I help you? 00:42:27
Hi, I'm Matthew, and this is Catherine. 00:42:29
And we're working on a problem. 00:42:31
It's a sound problem, and we really need to learn more about how high-frequency travels. 00:42:33
I may be able to help you. 00:42:38
Let me show you something that uses high-frequency sound. 00:42:39
Let me introduce you to a big brown bat. 00:42:43
Wow, does he bite? 00:42:46
No, you can touch him gently if you'd like. 00:42:48
Do bats use high-frequency sounds? 00:42:50
Sure, bats hunt in the dark. 00:42:53
They use high-frequency sounds and listen for the echoes in order to navigate and find food. 00:42:55
That's great. 00:42:59
We heard that high-frequency sounds don't travel very far. 00:43:00
Is that true for bats? 00:43:03
Yes, that's true. Air absorbs sound, especially high-frequency sound. 00:43:05
Some bats can hear things 60 feet away, but the average is only about 15 feet away. 00:43:09
In school, we just did an experiment on how fast sound travels. 00:43:15
This sounds amazing, but does it really help the bats? 00:43:19
Oh, yes, it does. 00:43:22
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. 00:43:23
In fact, in a perfectly dark room very much like this, 00:43:29
a bat can fly through without running into a moving wire that's as thin as a human hair. 00:43:32
In fact, a big brown bat can catch up to 600 mosquitoes in one hour. 00:43:38
600 mosquitoes an hour? 00:43:43
Doesn't that seem incredible? 00:43:45
Yeah. 00:43:46
Thanks, Mrs. Lewis. That was so fun. 00:43:47
Bye. Good luck. 00:43:50
Bye. 00:43:51
Now we need to figure out how to tell which things are making high-frequency noises. 00:43:52
Yeah, you're right. 00:43:56
Come on. 00:43:57
How do we figure out what's making these high-frequency sounds? 00:44:00
Let's do an Internet search and try to find a list of things that make high-frequency sounds. 00:44:03
Look up high-frequency. 00:44:08
How do I do that? 00:44:09
Just type in high-frequency sound. 00:44:10
That's pretty cool. 00:44:13
Have you ever started that? 00:44:14
Oh, look. Here it is. 00:44:16
Wow. What's an electronic dog repeller? 00:44:18
An electronic dog fight stopper. 00:44:21
That sounds weird. 00:44:23
And a pest zapper? 00:44:24
A toothbrush? 00:44:27
I didn't know toothbrushes had high-frequency sounds. 00:44:28
Those are electric ones. 00:44:31
Oh. 00:44:32
I wouldn't know much about that. 00:44:33
I had to brush my teeth by hand. 00:44:34
What should we do with this? 00:44:37
Let's email all the people who responded to our first email. 00:44:38
Let's ask them if they have any of these weird electronic devices. 00:44:41
That's a great idea. 00:44:45
Let's get busy. 00:44:46
Hey, guys. What are you doing today? 00:44:50
Oh, we're just playing around in your lab. 00:44:52
Just kidding. 00:44:54
We have a list of things that make high-frequency noises. 00:44:55
But we're not sure if we're on the right track. 00:44:58
We're hoping you can help us decide what we need to do next. 00:45:00
Let's review what we know. 00:45:02
We know that dogs can hear at very high frequencies, 00:45:04
much higher than human beings can hear. 00:45:06
At the museum, the bat creator told us that high-frequency sounds don't travel very far. 00:45:08
High and low-frequency sound travel is a really easy concept. 00:45:12
Do you have an experiment for us? 00:45:16
I certainly do. 00:45:18
In fact, I could do a little show-and-tell. 00:45:19
Would you like me to come to your class? 00:45:21
Yes, you can come to our class. 00:45:23
Oh, that would be great. 00:45:24
Boys and girls, this is Dr. D. 00:45:30
He's brought something really special to share with us today. 00:45:32
Good morning. 00:45:35
Good morning. 00:45:36
I already have an experiment set up. 00:45:38
It's going to show you the difference between high and low-frequency sounds. 00:45:40
Will we be able to see anything? 00:45:43
No, but you'll be able to hear it. 00:45:45
This machine is going to produce sounds at different frequencies. 00:45:47
I want you to raise your hand when you can't hear the sound anymore. 00:45:50
This is going to give you an idea about high and low-frequency sounds. 00:45:53
Here we go. 00:45:57
Oh, looks like we lost your teacher first. 00:46:16
I can't hear it either. 00:46:18
When you get older, you can't hear high-frequency sounds as well. 00:46:19
Let's keep going. 00:46:22
Ah, no one can hear it now. 00:46:30
I bet your dogs can still hear it. 00:46:32
Now we'll need some volunteers. 00:46:34
I'll take you and you and you and you. 00:46:36
I'm going to transmit a low-frequency sound to you. 00:46:43
PJ's going to put the phone between the speaker and your ear a couple of times. 00:46:46
Let's do it. 00:46:50
What happened? 00:46:53
The sound wasn't as loud. 00:46:55
Now I'm going to transmit a higher-frequency sound. 00:46:57
What happened this time? 00:47:07
It seemed like the sound was blocked off a lot more. 00:47:09
Let's try it again. Why don't you two switch places? 00:47:12
Okay. 00:47:14
Now PJ, did both sounds get softer when Jacob put the phonebook between the speaker and your ear? 00:47:16
Yes, but the higher-frequency sounds were a lot softer. 00:47:21
Now I'm going to transmit a higher-frequency sound. 00:47:24
What happened this time? 00:47:26
It seemed like the sound was blocked off a lot more. 00:47:28
Let's try it again. Why don't you two switch places? 00:47:31
Okay. 00:47:33
Why do you think so? 00:47:46
I don't know. Maybe you put the book closer to my ear. 00:47:48
The book was the same distance both times. 00:47:51
Remember, with the scientific method, we can only change one variable at a time. 00:47:54
I changed the frequency, so I'm glad Jacob was careful to keep the book distance the same both times. 00:47:59
I think that low-frequency sounds travel better than high-frequency sounds. 00:48:04
Well, low-frequency sounds do bend around corners a lot easier than high-frequency sounds. 00:48:08
That's why the lower-frequency sound was a little clearer because it bent around the phonebook. 00:48:13
This is so cool! 00:48:18
This experiment taught us that high-frequency sounds don't bend around corners very easily. 00:48:20
Don't forget what we learned about the bats. 00:48:25
How could we forget? 00:48:27
High-frequency bat calls don't travel very far. 00:48:29
What does all this mean? 00:48:31
Let's go back to our treehouse after school and think about it. 00:48:33
It's too bad PJ couldn't make it to the treehouse. 00:48:39
That sure was a great show and tell we had at school. 00:48:41
It really made it clear to me that high-frequency sounds don't bend around corners easily. 00:48:43
They only go in a straight line. 00:48:47
Let's get back to our need-to-know board. 00:48:48
We know that high-frequency sounds don't travel very far. 00:48:50
We know that it's not a low-frequency sound because humans aren't complaining about it. 00:48:53
We learned that from Ms. Sullivan at NASA. 00:48:57
We also know that high-frequency sounds can come from inside the house. 00:48:59
Remember our list? 00:49:02
We also need to know which neighborhoods are hearing barking and the item that is making the high-frequency sound. 00:49:04
Wow, look at all the emails we've received. 00:49:11
We better start separating them out. 00:49:13
I divided them into piles by subdivision. 00:49:15
Let's put them on a matrix board. 00:49:18
Oh, great, another matrix. 00:49:20
Hey, a matrix board can help you sort your information. 00:49:22
It may look hard, but don't sweat it. 00:49:25
Okay, okay, okay, let's get started. 00:49:27
On the matrix board, across the top, we have the subdivisions. 00:49:31
Midnight growl. 00:49:34
Cochlea cascade. 00:49:36
Sound seaside. 00:49:38
And the southern sleepless division. 00:49:40
Now down the side, let's put the possible causes. 00:49:42
Dog repellers, dog fight stoppers, pest zappers, and electronic toothbrushes. 00:49:45
Also on the side, let's put the effects. 00:49:50
Barking in the day and barking in the night. 00:49:53
Okay, in midnight growl, they still have dogs barking. 00:49:55
And they have dog repellers and toothbrushes. 00:49:59
And in the southern sleepless division, they have dogs barking and toothbrushes. 00:50:02
But on sound seaside, they have toothbrushes, but no dogs barking, so it can't be a toothbrush. 00:50:07
Let's not jump to conclusions before we analyze the data. 00:50:12
Analyzing the data could be a key to solving the problem. 00:50:15
In Cochlea cascade, they have dogs barking, dog repellers, dog fight stoppers, pest zappers, and toothbrushes. 00:50:18
Hmm, interesting, but I still don't get it. 00:50:27
The list is too long. I wouldn't want to have to test all those items. 00:50:29
I'm a well-rested Ted Toon with this special report. 00:50:38
Kids Science News Network has learned that bringing the barking dogs inside your house will only make the barking worse. 00:50:42
Whatever is making the dogs bark is definitely inside the houses of the residents of the city. 00:50:48
Not that I have to worry about it anymore. 00:50:54
More after this. 00:50:56
Wow, if the people took their dogs inside and the barking got worse, then maybe the sound is coming from inside the house. 00:50:58
Yeah, but what about the dogs that are barking outside? 00:51:04
The dogs inside probably made the dogs outside start barking. 00:51:07
You know, dogs respond to other dogs. 00:51:11
For a further report on the Gumsonic product recall, we go live to KSNN on-the-scene reporter, I Am Listening. 00:51:13
Thanks, Ted. Gumsonic issued a product recall. 00:51:20
Go ahead, I Am. 00:51:23
Ted, I already started. 00:51:24
Can she hear me? 00:51:25
Ted! 00:51:26
Oh, sorry, I Am. Please, go ahead. 00:51:27
As I was saying, Ted, Gumsonic issued a product recall for defective Gumsonic Turbo Model electric toothbrushes just days ago. 00:51:30
However, they have been unable to contact their best salesman, Mr. Big T. 00:51:39
Mr. Big T is currently selling the toothbrushes during a week-long Gumsonic door-to-door sales campaign. 00:51:45
If you happen to see Mr. T, please call... 00:51:52
Thanks, I Am. That was reporter, I Am Listening, on the scene. 00:51:54
I wasn't finished. 00:51:57
We'll be back after a message from... 00:51:58
Ted! 00:51:59
Oh, my mom bought one of those toothbrushes. Let's go to my house and check it out. 00:52:00
Okay. 00:52:04
I don't hear anything that annoying. 00:52:07
That's because it's very high frequency. 00:52:09
And this means the dogs can hear the frequency, but we can't because it's still too high. 00:52:11
Hey, look at Rocky. 00:52:16
It's okay, boy. 00:52:19
Did you see Rocky's reaction to the electric toothbrush? 00:52:20
And toothbrushes are on the list. 00:52:23
Do you think? 00:52:25
Do you think? 00:52:26
Do I think that that tiny toothbrush could be the source of the problem? 00:52:27
Hey, it's a possibility. 00:52:30
Remember on the Matrix board, every subdivision had toothbrushes. 00:52:32
But Sal and Cecil doesn't have any dogs barking. 00:52:35
Well, maybe that subdivision didn't buy any toothbrushes from the salesman. 00:52:38
That must be it. 00:52:42
Hey, I think I see Mr. Big T outside. 00:52:43
Hey, let's go catch him. 00:52:45
Okay. 00:52:47
Excuse me, sir. 00:52:49
Yes, what? What do you want? 00:52:50
Are you the faulty toothbrush salesman? 00:52:52
I mean, are you selling the Gump Sonic Turbo Model toothbrush? 00:52:54
Excuse me, young man. 00:52:57
I sell only quality toothbrushes. 00:52:58
There's absolutely no proof that they're faulty. 00:53:00
Did you see his teeth? 00:53:03
I can tell he's not using his toothbrush. 00:53:05
Okay, sir. 00:53:08
But aren't you the salesman that sells toothbrushes door to door? 00:53:09
Yes, that's me. 00:53:12
Best toothbrushes on the market. 00:53:13
Can I interest you in one? 00:53:14
No, thank you. 00:53:16
But you could tell us which subdivision you sell those toothbrushes to. 00:53:17
Um, let me get my list. 00:53:20
Let me see. 00:53:22
I sold them in Sleeping Subdivision, Midnight Growl, and Cochlear Cascade. 00:53:23
Did you sell any to Sound Seaside? 00:53:29
No, my competition beat me to the punch. 00:53:32
This could be it. 00:53:34
Those three subdivisions are where most of the barking took place. 00:53:35
Let's go tell Dr. D. 00:53:38
Bye. 00:53:40
Bye. 00:53:41
Wait, wait, guys. 00:53:42
Don't you want to buy a Gump Sonic Turbo Best Toothbrush in town? 00:53:43
Well, I can't wait to tell Dr. D. 00:53:48
Dr. D., we have some really great news. 00:53:51
What's the news? 00:53:54
We figured out the problem of the dogs barking. 00:53:55
It's all because of this. 00:53:57
Listen to this. 00:54:01
The toothbrushes were malfunctioning, 00:54:02
so they are producing at the frequency that the dogs could hear. 00:54:04
We learned that high frequencies travel a short distance in a straight line. 00:54:07
When people were using the toothbrushes in the early morning or the late night, 00:54:10
the sound was making the dogs bark. 00:54:14
We also learned that the noises coming from the dogs inside traveled to the outside. 00:54:16
And this set off barking from the dogs outside. 00:54:21
This is great. 00:54:24
Again, we learned that the scientific method really worked. 00:54:25
We identified the problem of the barking dogs. 00:54:28
Dog owners sent their observations by e-mail. 00:54:31
We learned that there were dogs barking early in the morning and late in the evening. 00:54:33
We learned through our research that dogs could hear sounds humans couldn't. 00:54:36
We gathered information from our experts, the web, and our e-mails. 00:54:40
All these things helped us eliminate possibilities. 00:54:44
We learned through our research and experimentation 00:54:47
that it couldn't be the factory because high frequency sounds don't bend around corners easily 00:54:50
and couldn't make it across town. 00:54:54
So as we found out, our first hypothesis wasn't correct. 00:54:56
I like the way you questioned your first hypothesis. 00:54:59
We did more research and listened to KSNN 00:55:02
and found out when the dogs were brought inside, it only made things worse. 00:55:05
So with some smart thinking, we figured out it must be an inside sound. 00:55:08
We narrowed our search and looked at our data 00:55:12
and we found out that toothbrushes had to be the logical choice. 00:55:14
Of course, we did confirm it with Mr. T. 00:55:17
We sure won't ever forget his face. 00:55:20
You scientific method did a great job. 00:55:23
What do we say? 00:55:25
All we can say is this. 00:55:27
The Treehouse Detectives solved yet another case. 00:55:28
Wa-la, wa-la, wa-la. 00:55:36
Wa-la. 00:55:39
I can't fix myself. 00:55:42
I've got one strand that keeps on falling out of the top. 00:55:49
I can't explain it. I can't explain it. I can't explain it. 00:55:52
All right, all right. 00:56:12
All right, all right. 00:56:32
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Idioma/s:
en
Niveles educativos:
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Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
684
Fecha:
28 de mayo de 2007 - 15:32
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
56′ 34″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
480x360 píxeles
Tamaño:
338.65 MBytes

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