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Science of Sound - Contenido educativo

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Connect segment exploring all the basics of sound including how it works and how it travels. The video also explains how the ear works.

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All right, I'm here at the Children's Museum of Virginia, located in Portsmouth, Virginia, 00:00:00
and this is Leslie Bowie, the museum's curator. 00:00:06
Hi, Leslie. 00:00:09
Hi, Van. 00:00:10
I understand you want to learn about sounds. 00:00:11
Yeah, I want to learn about how sound works and especially how sound travels. 00:00:12
Well, let's have a look at some of our exhibits and get the answers to those questions. 00:00:17
Okay. 00:00:22
The Children's Museum of Virginia is a place where kids can experience science firsthand. 00:00:23
Here they can feel it, touch it, explore it, learn it. 00:00:28
Let's first consider how sound is produced. 00:00:32
When sounds travel, we actually are hearing how the vibrations affect the air molecules. 00:00:34
A way I can demonstrate this is with a slinky. 00:00:39
Van, hold the other end, please. 00:00:42
What we perceive as sound is due to the alternate squeezing and stretching of molecules through 00:00:49
the air. 00:00:53
This, we refer to as sound waves. 00:00:54
Sound waves travel through the air at 344 meters per second. 00:00:57
They travel slower than light. 00:01:02
You can see this for yourself the next time you see a thunderstorm. 00:01:04
You can work out how far away the storm is from you by timing the interval between the 00:01:07
lightning and the clap of thunder. 00:01:11
A storm is about one mile away for every five seconds you count or one kilometer for every 00:01:14
three seconds. 00:01:19
Now that you know what sound is and how fast it travels, let's do some testing. 00:01:21
What do you notice? 00:01:26
The longer the tube, the lower the pitch. 00:01:28
Well, sure. 00:01:31
The air molecules in the long tube vibrate more slowly, producing a lower sound. 00:01:32
Higher sounds vibrate more quickly. 00:01:37
The difference in the number of vibrations per second we refer to as pitch. 00:01:40
Want to try? 00:01:44
Okay. 00:01:45
Cool. 00:01:55
We can also use a recorder to demonstrate pitch. 00:01:56
You use your fingers to lengthen and shorten the tube and create higher and lower notes. 00:01:59
Well, that's great, but how do you make it louder? 00:02:09
Well, with a recorder, just simply by blowing more air into the tube. 00:02:12
But there's another way to make sounds louder, and that's to focus sound. 00:02:16
Let's come have a look. 00:02:20
Okay. 00:02:21
Here, the parabolic dish collects sound from a huge area and funnels it right to this point. 00:02:23
If you're standing in just the right place, you can even hear a whisper. 00:02:30
So, Van, why was Mr. Murphy only bothered by your sound? 00:02:36
Wait. 00:02:40
Somebody just asked me about Mr. Murphy. 00:02:41
Who asked that question? 00:02:43
Well, Van, I'd like to introduce you to Dr. Lynette Roth. 00:02:45
Dr. Roth is an audiologist. 00:02:48
She specializes in hearing problems. 00:02:50
Oh, you mean like Mr. Murphy? 00:02:51
Well, the question I have is, how come he singled out my band when there were so many other noises in the neighborhood? 00:02:53
It might be, Van. 00:02:59
Like many older people, you couldn't hear the higher frequency of noise that came from the other sound sources. 00:03:00
The higher pitches? 00:03:05
Why? 00:03:07
Let me explain how the ear works first. 00:03:08
Sound waves travel through the air and enter the ear canal, causing the eardrum to vibrate. 00:03:11
The vibrations from the eardrum cause the three bones in the middle ear to move. 00:03:16
The last bone is called the stirrup. 00:03:20
The stirrup is attached to a thin membrane. 00:03:22
On the other side of this membrane is fluid housed inside a curled snail-shaped tube called the cochlea. 00:03:24
The vibrations from the stirrup causes this membrane to flex, which in turn sets the fluid into motion. 00:03:30
The moving fluid tickles thousands of delicate microscopic hair-like cells called cilia. 00:03:36
The cilia convert the vibrations into electric nerve impulses, which the brain interprets as sound. 00:03:41
High frequencies are heard by the cilia at the beginning of the cochlea. 00:03:47
Lower frequencies are heard at the end. 00:03:50
If the sound intensity is too great, or if it happens for a prolonged period of time, 00:03:53
the cells will die at the beginning of the cochlea. 00:03:57
Sound energy, or intensity, is measured in decibels. 00:04:00
Generally speaking, the human ear can comfortably hear between 10 to 80 decibels. 00:04:03
A quiet library typically registers between 40 to 60 decibels, 00:04:08
while a loud rock concert registers above 110 decibels. 00:04:12
Van, it's likely Mr. Murphy has lost some of his ability to hear at high frequencies. 00:04:16
So this explains why Mr. Murphy singled out our band. 00:04:20
Yes, Van, but I'm more concerned about the ear safety of young people, and in particular the noodles. 00:04:25
Be careful how loud you practice your music, not for Mr. Murphy's comfort, but for your safety as well. 00:04:30
You bet. Dr. Roth, Mrs. Bowie, thanks for letting me come over to the Children's Museum of Virginia 00:04:35
to learn about sound and how the ear works. 00:04:40
Okay, I now have a better understanding of the science of sound and how people hear, 00:04:43
but how do I control the amount of sound coming from my garage? 00:04:48
Well, to find the answer to that, we're going to go back to Shelly at NASA Langley 00:04:52
to see what she's learning about noise abatement. 00:04:55
Perhaps she can pick up a tip or two I can use. 00:04:57
Meanwhile, I'll share this information with my band, and I'll catch you later. 00:04:59
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Idioma/s:
en
Materias:
Matemáticas
Niveles educativos:
▼ Mostrar / ocultar niveles
      • Nivel Intermedio
Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
448
Fecha:
28 de mayo de 2007 - 16:53
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
05′ 04″
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:
30.44 MBytes

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