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Acoustics Research - Contenido educativo

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Connect segment exploring the research and study efforts applied towards acoustics and noise, especially that related to aircraft. The segment also explains the study of psychological effects of noise on people.

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Oh, great. You're just in time. Everybody, let me introduce you to Brenda Sullivan and 00:00:00
Rich Silcox. We're here at NASA Langley in a building where they do acoustical research. 00:00:07
Let's go here first to Rich. You are a senior research engineer, right? 00:00:13
Correct. 00:00:17
All right. And Brenda, hmm, I'm going to get this name wrong. Brenda, you are a psychoacoustician. 00:00:18
Now, can you correct my wording and then tell me a little bit about what that is? 00:00:23
Well, I'm a psychoacoustician. Psychoacoustician is somebody who designs, conducts, and analyzes 00:00:27
tests to study the psychological effects of noise on people. 00:00:34
Oh, psychological effects. Now, that's kind of interesting. And Rich, how about you? Can 00:00:38
you describe for us just what exactly is a senior research engineer? 00:00:42
Well, Shelly, there's a lot of noise research that goes on here relating to aircraft noise. 00:00:46
And I work with researchers both here and at NASA Glenn in Ohio and NASA Ames in California 00:00:50
to come up with ways to reduce the noise that aircraft make. The word acoustics means 00:00:55
the scientific study of sound and how the qualities of space affect sound to transmit 00:01:00
well or poorly. 00:01:05
Why don't we begin with the research that Brenda's doing? Brenda, why don't you introduce 00:01:08
Shelly to your fellow sound researcher? 00:01:12
Certainly. Shelly, meet Fred the Head. 00:01:14
This is Fred? 00:01:16
This is Fred. Fred and his friend Norm here are essentially my research. Testing for noise 00:01:17
starts with deciding what aspect of noise to study. For instance, the sound in a community 00:01:23
near an airport or the noises inside an actual airplane. 00:01:28
See, that's where Norm comes in. I take him up in the air inside the airplane so he can 00:01:32
record the noises that are in there in flight. See, he's got a microphone in each ear. They're 00:01:37
kind of hard to see on Norm. They're easier to see on Fred. Let me show you. 00:01:42
Okay. 00:01:45
Ouch! 00:01:46
It's all right. He's used to that sort of treatment. See, he's got a mic in there. It's 00:01:47
hard to see. Let me take his skull off. 00:01:51
Oh, wow. 00:01:53
See, he has a microphone in each ear. 00:01:54
Anyway, these little microphones record the sound that's heard by each ear just as you 00:01:57
would hear it yourself. I take these binaural recordings I make with Norm and bring them 00:02:01
back to the lab. I can edit them on the computer and play them back to the people who come 00:02:07
in to act as subjects in my tests. For instance, I can take some of the tones made by the propellers 00:02:11
of a plane and reduce them. And people can tell me if they prefer the reduced versions 00:02:16
and how much they prefer them so that we can predict their reactions to future noises. 00:02:21
Oh, how interesting. 00:02:25
Shelly, if you'd like, I can arrange to show you NASA's 757 research aircraft. And I can 00:02:26
show you the physics involved in producing the sound and how one goes about controlling 00:02:32
the sound. 00:02:36
Oh, man, that would be so cool. I know I'd be interested. I'm sure the viewers would 00:02:37
be interested in seeing a real live NASA jumbo jet research plane. 00:02:39
Shelly, this is the NASA 757 in which we conduct various types of research. NASA has a ten-year 00:02:51
goal to reduce noise impact from aircraft so that communities hear one half the noise 00:02:57
that they heard in 1997. The amount of noise reduction is similar to the difference between 00:03:02
heavy traffic noise and light traffic noise. The noise impact reduction effort is led by 00:03:06
NASA Langley Research Center and is conducted in close partnership with NASA Glenn Research 00:03:11
Center in Ohio and NASA Ames Research Center in California, along with help from academia, 00:03:17
industry and the FAA. 00:03:23
Wow, this aircraft is huge. Where do you even begin to start to find the many sources of 00:03:25
noise that must come from this aircraft? 00:03:30
In some modern aircraft like this 757, a lot of noise is generated from the air turbulence 00:03:32
created by the wing flaps, slats and landing gear slicing through the air. To control this 00:03:37
type of noise, we use computers to create detailed models of the airflow over these 00:03:43
surfaces and look for ways to smooth out the flow and reduce the turbulence. 00:03:48
Shelly, of course, most of the noise is produced by the jet engine. Modern jet engines have 00:03:52
these large fans that move large volumes of air through the engines. However, the fan 00:03:57
itself produces what we call fan tones. This type of noise is reduced by treating the inlet 00:04:02
and exhaust duct with special acoustic liners, sort of like towels for office ceilings. 00:04:07
And Shelly, the biggest noise problem we have is that of jet exhaust noise. And working 00:04:12
with us in jet exhaust noise is Martha Brown. Hi, Martha. 00:04:18
Hi, Rich. 00:04:21
Hi, Martha. Hi, Shelly. 00:04:22
Martha, Shelly has a particular problem in noise abatement. I was wondering if you could 00:04:24
explain to Martha what it is. 00:04:28
Yeah, thanks, Rich. My problem is that I'm trying to get some pointers on how to reduce 00:04:29
noise for my friend Van and his band, The Noodles. They rehearse in a garage. It seems 00:04:34
that their rehearsals are disturbing the neighbor as he's trying to take a nap. So we're trying 00:04:39
to figure out how can we reduce the noise or the sound coming out of the garage. Do 00:04:43
you think you can help? 00:04:47
I'll be glad to help. But first, let me tell you a little bit about myself and what I do 00:04:48
at NASA Langley. 00:04:52
Okay. 00:04:53
I work as an engineer in the Jet Noise Laboratory. I study ways to change the air coming out 00:04:54
of a jet with the hope of reducing noise created by this air. High-speed air is needed to 00:04:58
move an airplane forward. I work with a team of engineers to invent ways to change the 00:05:04
speed of the air exiting the jet by jet mixing. 00:05:09
So just how do you increase jet mixing? 00:05:13
Well, Shelly, we use non-round shapes like this rectangle nozzle, this elliptical nozzle, 00:05:15
and also this corrugated nozzle. 00:05:25
Oh, now this reminds me of a flower with petals. 00:05:27
I see what you mean. But in fact, they're called lobes. 00:05:30
Lobes? 00:05:33
Yes. And also we may change the round nozzle and how it looks by adding tabs at the ends 00:05:34
that you see here. 00:05:40
Oh, now these tabs look like shark teeth. So what other ways do you have to reduce noise? 00:05:41
Well, Shelly, we use materials to line the inside of the nozzle. You see, this is called 00:05:47
a liner. And what it's used to do is to absorb the sound before it exits the nozzle. 00:05:55
Like a muffler? 00:06:01
Yes. 00:06:02
Okay, let's go back to Van now. What one point might you make back to Van that could help 00:06:03
him with his problem? 00:06:08
I recommend that he buy ceiling tiles to line the ceiling of his garage. 00:06:10
Oh, okay. 00:06:15
And Shelly, he can install carpet on the floor and draperies on the windows to help reduce 00:06:16
the sound. 00:06:20
Oh, Rich and Martha, that's great sound advice. And I will share that back with Van. Thank 00:06:21
you so much. 00:06:26
You're very welcome. 00:06:27
All right. And to the rest of you, gang, I'm going to send you to find Van and see what 00:06:28
he's up to. Meanwhile, I'm going to head back to the NASA Connect studio and get ready for 00:06:32
our special guest. And if you haven't thought of some questions, think about some because 00:06:35
in a moment, you'll be able to call in with your questions. I'll see you back at the studio. 00:06:39
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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:
171
Fecha:
28 de mayo de 2007 - 16:53
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
06′ 44″
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:
40.45 MBytes

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