1 00:00:00,000 --> 00:00:10,000 TAP FOR SOUND 2 00:00:30,000 --> 00:00:37,000 TAP FOR SOUND 3 00:00:38,000 --> 00:00:40,000 TAP FOR SOUND 4 00:00:40,000 --> 00:00:41,000 TAP FOR SOUND 5 00:00:41,000 --> 00:00:42,000 What is that noise? 6 00:00:42,000 --> 00:00:49,000 TAP FOR SOUND 7 00:00:49,000 --> 00:00:50,000 Watch out! 8 00:00:50,000 --> 00:00:54,000 TAP FOR SOUND 9 00:00:54,000 --> 00:01:01,000 TAP FOR SOUND 10 00:01:01,000 --> 00:01:03,000 TAP FOR SOUND 11 00:01:03,000 --> 00:01:17,000 TAP FOR SOUND 12 00:01:17,000 --> 00:01:21,000 TAP FOR SOUND 13 00:01:21,000 --> 00:01:26,000 TAP FOR SOUND 14 00:01:26,000 --> 00:01:32,000 TAP FOR SOUND 15 00:01:32,000 --> 00:01:34,000 Hi, Van! Hey! 16 00:01:34,000 --> 00:01:35,000 Hey! 17 00:01:35,000 --> 00:01:37,000 Hey, hey, I gotta ask you a question. 18 00:01:37,000 --> 00:01:39,000 What was all that about out there? 19 00:01:39,000 --> 00:01:41,000 Well, Mr. Murphy seems to think that, uh, 20 00:01:41,000 --> 00:01:45,000 practicing for the NASCONet cast party was disturbing his nap. 21 00:01:45,000 --> 00:01:48,000 I don't even see how he could hear us from all those other noises outside. 22 00:01:48,000 --> 00:01:50,000 Well, I know what you mean. I mean, he was talking to me. 23 00:01:50,000 --> 00:01:52,000 I couldn't even hear him because of the plane that was passing by. 24 00:01:52,000 --> 00:01:55,000 We can't hardly even hear ourselves because the plane's around here. 25 00:01:55,000 --> 00:01:56,000 Let me introduce you to the band. 26 00:01:56,000 --> 00:01:57,000 Oh, great. 27 00:01:57,000 --> 00:01:59,000 We have Ben Googler on the bass guitar. 28 00:02:03,000 --> 00:02:05,000 Nick Bartolotta on the drums. 29 00:02:07,000 --> 00:02:09,000 And Tyler Cain on the keyboard. 30 00:02:11,000 --> 00:02:12,000 So, you ready to hear our song? 31 00:02:12,000 --> 00:02:14,000 Uh, no, I don't think so, guys. 32 00:02:14,000 --> 00:02:17,000 You know, given your little visit you just had from Murphy, 33 00:02:17,000 --> 00:02:21,000 don't you think you might need to think about reducing the noise level 34 00:02:21,000 --> 00:02:22,000 instead of practicing right now? 35 00:02:22,000 --> 00:02:24,000 Well, we could just close the garage door. 36 00:02:24,000 --> 00:02:26,000 Well, yeah, Van, I'm sure that would help. 37 00:02:26,000 --> 00:02:29,000 But you know, somehow I think if you had a little bit more knowledge 38 00:02:29,000 --> 00:02:32,000 about the science behind sound and sound properties 39 00:02:32,000 --> 00:02:34,000 that you and your band might be able to reduce your noise level 40 00:02:34,000 --> 00:02:36,000 just a little bit further. 41 00:02:36,000 --> 00:02:38,000 Matter of fact, I know. 42 00:02:38,000 --> 00:02:41,000 I've got some friends at NASCON Langley who are studying noise abatement. 43 00:02:41,000 --> 00:02:44,000 That is, how do you eliminate or reduce noise? 44 00:02:44,000 --> 00:02:49,000 Maybe they could give us some insights as to how to stop disturbing poor Mr. Murphy. 45 00:02:49,000 --> 00:02:52,000 Hey, guys, the Children's Museum of Virginia in Portsmouth 46 00:02:52,000 --> 00:02:54,000 has some information about sound. 47 00:02:54,000 --> 00:02:56,000 It's not too far from here. 48 00:02:56,000 --> 00:02:57,000 Hey, that's a great idea. 49 00:02:57,000 --> 00:03:00,000 You know, I think that would be a great place to start. 50 00:03:00,000 --> 00:03:02,000 So, Van, why don't you and the band kind of pack up, 51 00:03:02,000 --> 00:03:06,000 head on over to the museum and see what you can learn about sound. 52 00:03:06,000 --> 00:03:08,000 Meanwhile, I'll head on over to NASA, 53 00:03:08,000 --> 00:03:12,000 contact some acoustical researchers at NASA Langley in Hampton, Virginia, 54 00:03:12,000 --> 00:03:15,000 and see what I can learn about noise control. 55 00:03:15,000 --> 00:03:17,000 And, gang, you're invited along also. 56 00:03:17,000 --> 00:03:18,000 You're part of the sound team. 57 00:03:18,000 --> 00:03:21,000 So as we go along, we want you to take some sound notes 58 00:03:21,000 --> 00:03:23,000 as we interview each of our program guests. 59 00:03:23,000 --> 00:03:25,000 And as we go through the show, 60 00:03:25,000 --> 00:03:28,000 you'll be challenged to analyze data from an experiment about sound 61 00:03:28,000 --> 00:03:32,000 that students at Ruffner Middle School in Norfolk, Virginia, performed for NASA. 62 00:03:32,000 --> 00:03:35,000 And with the help of our program partner, the FAA, 63 00:03:35,000 --> 00:03:37,000 students from Lexington, Massachusetts, 64 00:03:37,000 --> 00:03:42,000 will also join us with some tech talk about the Quiet in the Skies website. 65 00:03:42,000 --> 00:03:45,000 And speaking of the website, when you see this sign, 66 00:03:45,000 --> 00:03:48,000 that's your clue to check out the cool NASA Connect website 67 00:03:48,000 --> 00:03:52,000 for further information and activities related to today's topic. 68 00:03:52,000 --> 00:03:54,000 And as we go along in this program, 69 00:03:54,000 --> 00:03:56,000 I'd like you to be thinking about some questions 70 00:03:56,000 --> 00:03:59,000 that you can phone or e-mail into our researchers during today's program. 71 00:03:59,000 --> 00:04:03,000 Now then, Nick, how about a little drum roll, please? 72 00:04:03,000 --> 00:04:06,000 Ready, gang? Let's shake, rattle, and roll! 73 00:04:10,000 --> 00:04:13,000 All right, I'm here at the Children's Museum of Virginia, 74 00:04:13,000 --> 00:04:15,000 located in Portsmouth, Virginia. 75 00:04:15,000 --> 00:04:17,000 And this is Leslie Bowie, the museum's curator. 76 00:04:17,000 --> 00:04:18,000 Hi, Leslie. 77 00:04:18,000 --> 00:04:21,000 Hi, Van. I understand you want to learn about sounds. 78 00:04:21,000 --> 00:04:25,000 Yeah, I want to learn about how sound works and especially how sound travels. 79 00:04:25,000 --> 00:04:28,000 Well, let's have a look at some of our exhibits 80 00:04:28,000 --> 00:04:30,000 and get the answers to those questions. 81 00:04:30,000 --> 00:04:31,000 Okay. 82 00:04:32,000 --> 00:04:34,000 The Children's Museum of Virginia is a place 83 00:04:34,000 --> 00:04:37,000 where kids can experience science firsthand. 84 00:04:37,000 --> 00:04:40,000 Here they can feel it, touch it, explore it, learn it. 85 00:04:40,000 --> 00:04:43,000 Let's first consider how sound is produced. 86 00:04:43,000 --> 00:04:45,000 When sounds travel, we actually are hearing 87 00:04:45,000 --> 00:04:48,000 how the vibrations affect the air molecules. 88 00:04:48,000 --> 00:04:51,000 A way I can demonstrate this is with a slinky. 89 00:04:51,000 --> 00:04:53,000 Van, hold the other end, please. 90 00:04:54,000 --> 00:05:00,000 What we perceive as sound is due to the alternate squeezing 91 00:05:00,000 --> 00:05:02,000 and stretching of molecules through the air. 92 00:05:02,000 --> 00:05:05,000 This we refer to as sound waves. 93 00:05:05,000 --> 00:05:10,000 Sound waves travel through the air at 344 meters per second. 94 00:05:10,000 --> 00:05:12,000 They travel slower than light. 95 00:05:12,000 --> 00:05:15,000 You can see this for yourself the next time you see a thunderstorm. 96 00:05:15,000 --> 00:05:18,000 You can work out how far away the storm is from you 97 00:05:18,000 --> 00:05:22,000 by timing the interval between the lightning and the clap of thunder. 98 00:05:22,000 --> 00:05:26,000 A storm is about one mile away for every five seconds you count, 99 00:05:26,000 --> 00:05:29,000 or one kilometer for every three seconds. 100 00:05:29,000 --> 00:05:32,000 Now that you know what sound is and how fast it travels, 101 00:05:32,000 --> 00:05:34,000 let's do some testing. 102 00:05:36,000 --> 00:05:37,000 What do you notice? 103 00:05:37,000 --> 00:05:40,000 The longer the tube, the lower the pitch. 104 00:05:40,000 --> 00:05:41,000 Well, sure. 105 00:05:41,000 --> 00:05:44,000 The air molecules in the long tube vibrate more slowly, 106 00:05:44,000 --> 00:05:46,000 producing a lower sound. 107 00:05:46,000 --> 00:05:49,000 Higher sounds vibrate more quickly. 108 00:05:49,000 --> 00:05:53,000 The difference in the number of vibrations per second we refer to as pitch. 109 00:05:53,000 --> 00:05:54,000 Want to try? 110 00:05:54,000 --> 00:05:55,000 Okay. 111 00:06:04,000 --> 00:06:05,000 Cool. 112 00:06:05,000 --> 00:06:08,000 We can also use a recorder to demonstrate pitch. 113 00:06:08,000 --> 00:06:11,000 You use your fingers to lengthen and shorten the tube 114 00:06:11,000 --> 00:06:13,000 and create higher and lower notes. 115 00:06:14,000 --> 00:06:18,000 ♪ 116 00:06:18,000 --> 00:06:21,000 Well, that's great, but how do you make it louder? 117 00:06:21,000 --> 00:06:25,000 Well, with a recorder, just simply by blowing more air into the tube. 118 00:06:25,000 --> 00:06:27,000 But there's another way to make sounds louder, 119 00:06:27,000 --> 00:06:29,000 and that's to focus sound. 120 00:06:29,000 --> 00:06:30,000 Let's come have a look. 121 00:06:30,000 --> 00:06:31,000 Okay. 122 00:06:33,000 --> 00:06:37,000 Here, the parabolic dish collects sound from a huge area 123 00:06:37,000 --> 00:06:39,000 and funnels it right to this point. 124 00:06:39,000 --> 00:06:43,000 If you're standing in just the right place, you can even hear a whisper. 125 00:06:45,000 --> 00:06:49,000 So, Van, why was Mr. Murphy only bothered by your sound? 126 00:06:49,000 --> 00:06:50,000 Wait. 127 00:06:50,000 --> 00:06:52,000 Somebody just asked me about Mr. Murphy. 128 00:06:52,000 --> 00:06:54,000 Who asked that question? 129 00:06:54,000 --> 00:06:57,000 Well, Van, I'd like to introduce you to Dr. Lynette Roth. 130 00:06:57,000 --> 00:06:59,000 Dr. Roth is an audiologist. 131 00:06:59,000 --> 00:07:01,000 She specializes in hearing problems. 132 00:07:01,000 --> 00:07:03,000 Oh, you mean like Mr. Murphy? 133 00:07:03,000 --> 00:07:07,000 Well, the question I have is, how come he singled out my band 134 00:07:07,000 --> 00:07:09,000 when there were so many other noises in the neighborhood? 135 00:07:09,000 --> 00:07:10,000 It might be, Van. 136 00:07:10,000 --> 00:07:13,000 Like many older people, you couldn't hear the higher frequency of noise 137 00:07:13,000 --> 00:07:15,000 that came from the other sound sources. 138 00:07:15,000 --> 00:07:17,000 The higher pitches? Why? 139 00:07:17,000 --> 00:07:20,000 Let me explain how the ear works first. 140 00:07:20,000 --> 00:07:24,000 Sound waves travel through the air and enter the ear canal, 141 00:07:24,000 --> 00:07:26,000 causing the eardrum to vibrate. 142 00:07:26,000 --> 00:07:30,000 The vibrations from the eardrum cause the three bones in the middle ear to move. 143 00:07:30,000 --> 00:07:32,000 The last bone is called the stirrup. 144 00:07:32,000 --> 00:07:34,000 The stirrup's attached to a thin membrane. 145 00:07:34,000 --> 00:07:36,000 On the other side of this membrane is fluid 146 00:07:36,000 --> 00:07:40,000 housed inside a curled snail-shaped tube called the cochlea. 147 00:07:40,000 --> 00:07:43,000 The vibrations from the stirrup causes this membrane to flex, 148 00:07:43,000 --> 00:07:46,000 which in turn sets the fluid into motion. 149 00:07:46,000 --> 00:07:48,000 The moving fluid tickles thousands of delicate, 150 00:07:48,000 --> 00:07:51,000 microscopic hair-like cells called cilia. 151 00:07:51,000 --> 00:07:54,000 The cilia convert the vibrations into electric nerve impulses, 152 00:07:54,000 --> 00:07:56,000 which the brain interprets as sound. 153 00:07:56,000 --> 00:07:59,000 High frequencies are heard by the cilia at the beginning of the cochlea. 154 00:07:59,000 --> 00:08:02,000 Lower frequencies are heard at the end. 155 00:08:02,000 --> 00:08:04,000 If sound intensity is too great, 156 00:08:04,000 --> 00:08:07,000 or if it happens for a prolonged period of time, 157 00:08:07,000 --> 00:08:10,000 the cells will die at the beginning of the cochlea. 158 00:08:10,000 --> 00:08:13,000 Sound energy, or intensity, is measured in decibels. 159 00:08:13,000 --> 00:08:18,000 Generally speaking, the human ear can comfortably hear between 10 to 80 decibels. 160 00:08:18,000 --> 00:08:22,000 A quiet library typically registers between 40 to 60 decibels, 161 00:08:22,000 --> 00:08:26,000 while a loud rock concert registers above 110 decibels. 162 00:08:26,000 --> 00:08:30,000 Van, it's likely Mr. Murphy has lost some of his ability to hear at high frequencies. 163 00:08:30,000 --> 00:08:35,000 So this explains why Mr. Murphy singled out our band. 164 00:08:35,000 --> 00:08:38,000 Yes, Van, but I'm more concerned about the ear safety of young people, 165 00:08:38,000 --> 00:08:39,000 and in particular the noodles. 166 00:08:39,000 --> 00:08:41,000 Be careful how loud you practice your music, 167 00:08:41,000 --> 00:08:44,000 not for Mr. Murphy's comfort, but for your safety as well. 168 00:08:44,000 --> 00:08:45,000 You bet. 169 00:08:45,000 --> 00:08:47,000 Dr. Roth, Mrs. Bowie, 170 00:08:47,000 --> 00:08:50,000 thanks for letting me come over to the Children's Museum of Virginia 171 00:08:50,000 --> 00:08:52,000 to learn about sound and how the ear works. 172 00:08:52,000 --> 00:08:58,000 Okay, I now have a better understanding of the science of sound and how people hear, 173 00:08:58,000 --> 00:09:01,000 but how do I control the amount of sound coming from my garage? 174 00:09:01,000 --> 00:09:04,000 Well, to find the answer to that, we're going to go back to Shelly at NASA Langley 175 00:09:04,000 --> 00:09:06,000 to see what she's learning about noise abatement. 176 00:09:06,000 --> 00:09:08,000 Perhaps she can pick up a tip or two I can use. 177 00:09:08,000 --> 00:09:12,000 Meanwhile, I'll share this information with my band, and I'll catch you later. 178 00:09:15,000 --> 00:09:17,000 Oh, great, you're just in time. 179 00:09:17,000 --> 00:09:21,000 Everybody, let me introduce you to Brenda Sullivan and Rich Silcox. 180 00:09:21,000 --> 00:09:25,000 We're here at NASA Langley in a building where they do acoustical research. 181 00:09:25,000 --> 00:09:27,000 Let's go here first to Rich. 182 00:09:27,000 --> 00:09:29,000 You are a senior research engineer, right? 183 00:09:29,000 --> 00:09:30,000 Correct. 184 00:09:30,000 --> 00:09:33,000 All right, and Brenda, I'm going to get this name wrong. 185 00:09:33,000 --> 00:09:35,000 Brenda, you are a psychacoustician. 186 00:09:35,000 --> 00:09:40,000 Now, can you correct my wording and then tell me a little bit about what that is? 187 00:09:40,000 --> 00:09:42,000 Well, I'm a psychoacoustician. 188 00:09:42,000 --> 00:09:48,000 Psychoacoustician is somebody who designs, conducts, and analyzes tests 189 00:09:48,000 --> 00:09:51,000 to study the psychological effects of noise on people. 190 00:09:51,000 --> 00:09:54,000 Oh, psychological effects, now that's kind of interesting. 191 00:09:54,000 --> 00:09:55,000 And, Rich, how about you? 192 00:09:55,000 --> 00:09:59,000 Can you describe for us just what exactly is a senior research engineer? 193 00:09:59,000 --> 00:10:03,000 Well, Shelly, there's a lot of noise research that goes on here relating to aircraft noise, 194 00:10:03,000 --> 00:10:07,000 and I work with researchers both here and at NASA Glenn in Ohio, 195 00:10:07,000 --> 00:10:12,000 and NASA Ames in California to come up with ways to reduce the noise that aircraft make. 196 00:10:12,000 --> 00:10:15,000 The word acoustics means the scientific study of sound 197 00:10:15,000 --> 00:10:20,000 and how the qualities of space affect sound to transmit well or poorly. 198 00:10:20,000 --> 00:10:23,000 Why don't we begin with the research that Brenda's doing? 199 00:10:23,000 --> 00:10:27,000 Brenda, why don't you introduce Shelly to your fellow sound researcher? 200 00:10:27,000 --> 00:10:29,000 Certainly. Shelly, meet Fred the Head. 201 00:10:29,000 --> 00:10:30,000 This is Fred. 202 00:10:30,000 --> 00:10:31,000 This is Fred. 203 00:10:31,000 --> 00:10:35,000 Fred and his friend Norm here are essentially my research. 204 00:10:35,000 --> 00:10:39,000 Testing for noise starts with deciding what aspect of noise to study. 205 00:10:39,000 --> 00:10:45,000 For instance, the sound in a community near an airport or the noises inside an actual airplane. 206 00:10:45,000 --> 00:10:47,000 See, that's where Norm comes in. 207 00:10:47,000 --> 00:10:52,000 I take him up in the air inside the airplane so he can record the noises in there in flight. 208 00:10:52,000 --> 00:10:54,000 See, he's got a microphone in each ear. 209 00:10:54,000 --> 00:10:57,000 They're kind of hard to see on Norm. They're easier to see on Fred. 210 00:10:57,000 --> 00:10:58,000 Let me show you. 211 00:10:58,000 --> 00:10:59,000 Okay. 212 00:10:59,000 --> 00:11:00,000 Ouch! 213 00:11:00,000 --> 00:11:02,000 It's all right. He's used to that sort of treatment. 214 00:11:02,000 --> 00:11:06,000 See, he's got a mic in there. It's hard to see. Let me take his skull off. 215 00:11:06,000 --> 00:11:08,000 Oh, wow. 216 00:11:08,000 --> 00:11:10,000 See, he has a microphone in each ear. 217 00:11:10,000 --> 00:11:14,000 Anyway, these little microphones record the sound that's heard by each ear, 218 00:11:14,000 --> 00:11:16,000 just as you would hear it yourself. 219 00:11:16,000 --> 00:11:20,000 I take these binaural recordings I make with Norm and bring them back to the lab. 220 00:11:20,000 --> 00:11:25,000 I can edit them on the computer and play them back to the people who come in to act as subjects in my tests. 221 00:11:25,000 --> 00:11:30,000 For instance, I can take some of the tones made by the propellers of a plane and reduce them. 222 00:11:30,000 --> 00:11:35,000 And people can tell me if they prefer the reduced versions and how much they prefer them, 223 00:11:35,000 --> 00:11:37,000 so that we can predict their reactions to future noises. 224 00:11:37,000 --> 00:11:39,000 Oh, how interesting. 225 00:11:39,000 --> 00:11:44,000 Shelly, if you'd like, I can arrange to show you NASA's 757 research aircraft, 226 00:11:44,000 --> 00:11:49,000 and I can show you the physics involved in producing the sound and how one goes about controlling the sound. 227 00:11:49,000 --> 00:11:50,000 Oh, man, that would be so cool. 228 00:11:50,000 --> 00:11:52,000 I know I'd be interested. 229 00:11:52,000 --> 00:11:56,000 I'm sure the viewers would be interested in seeing a real live NASA Jumbo Jet research plane. 230 00:11:56,000 --> 00:12:04,000 Music 231 00:12:04,000 --> 00:12:09,000 Shelly, this is the NASA 757 in which we conduct various types of research. 232 00:12:09,000 --> 00:12:12,000 NASA has a ten-year goal to reduce noise impact from aircraft 233 00:12:12,000 --> 00:12:17,000 so that communities hear one-half the noise that they heard in 1997. 234 00:12:17,000 --> 00:12:22,000 The amount of noise reduction is similar to the difference between heavy traffic noise and light traffic noise. 235 00:12:22,000 --> 00:12:26,000 The noise impact reduction effort is led by NASA Langley Research Center 236 00:12:26,000 --> 00:12:31,000 and is conducted in close partnership with NASA Glenn Research Center in Ohio 237 00:12:31,000 --> 00:12:34,000 and NASA Ames Research Center in California, 238 00:12:34,000 --> 00:12:38,000 along with help from academia, industry, and the FAA. 239 00:12:38,000 --> 00:12:40,000 Wow, this aircraft is huge. 240 00:12:40,000 --> 00:12:45,000 Where do you even begin to start to find the many sources of noise that must come from this aircraft? 241 00:12:45,000 --> 00:12:50,000 In some modern aircraft like this 757, a lot of noise is generated from the air turbulence 242 00:12:50,000 --> 00:12:56,000 created by the wing flaps, slats, and landing gear slicing through the air. 243 00:12:56,000 --> 00:13:02,000 To control this type of noise, we use computers to create detailed models of the airflow over these surfaces 244 00:13:02,000 --> 00:13:06,000 and look for ways to smooth out the flow and reduce the turbulence. 245 00:13:06,000 --> 00:13:10,000 Shelly, of course, most of the noise is produced by the jet engine. 246 00:13:10,000 --> 00:13:15,000 Modern jet engines have these large fans that move large volumes of air through the engines. 247 00:13:15,000 --> 00:13:18,000 However, the fan itself produces what we call fan tones. 248 00:13:18,000 --> 00:13:23,000 This type of noise is reduced by treating the inlet and exhaust duct with special acoustic liners, 249 00:13:23,000 --> 00:13:27,000 sort of like towels for office ceilings. 250 00:13:27,000 --> 00:13:31,000 And Shelly, the biggest noise problem we have is that of jet exhaust noise. 251 00:13:31,000 --> 00:13:33,000 And working with us in jet exhaust noise is Martha Brown. 252 00:13:33,000 --> 00:13:34,000 Hi, Martha. 253 00:13:34,000 --> 00:13:35,000 Hi, Rich. 254 00:13:35,000 --> 00:13:36,000 Hi, Martha. 255 00:13:36,000 --> 00:13:37,000 Hi, Shelly. 256 00:13:37,000 --> 00:13:40,000 Martha, Shelly has a particular problem in noise abatement. 257 00:13:40,000 --> 00:13:42,000 I was wondering if you could explain to Martha what it is. 258 00:13:42,000 --> 00:13:43,000 Yeah, thanks, Rich. 259 00:13:43,000 --> 00:13:50,000 My problem is that I'm trying to get some pointers on how to reduce noise for my friend Van and his band, The Noodles. 260 00:13:50,000 --> 00:13:56,000 They rehearse in a garage, and it seems that their rehearsals are disturbing the neighbor as he's trying to take a nap. 261 00:13:56,000 --> 00:14:00,000 So we're trying to figure out how can we reduce the noise or the sound coming out of the garage. 262 00:14:00,000 --> 00:14:01,000 Do you think you can help? 263 00:14:01,000 --> 00:14:02,000 I'll be glad to help. 264 00:14:02,000 --> 00:14:06,000 But first, let me tell you a little bit about myself and what I do at NASA Langley. 265 00:14:06,000 --> 00:14:09,000 I work as an engineer in the Jet Noise Laboratory. 266 00:14:09,000 --> 00:14:15,000 I study ways to change the air coming out of a jet with the hope of reducing noise created by this air. 267 00:14:15,000 --> 00:14:19,000 High-speed air is needed to move an airplane forward. 268 00:14:19,000 --> 00:14:26,000 I work with a team of engineers to invent ways to change the speed of the air exiting the jet by jet mixing. 269 00:14:26,000 --> 00:14:29,000 So just how do you increase jet mixing? 270 00:14:29,000 --> 00:14:40,000 Well, Shelly, we use non-round shapes like this rectangle nozzle, this elliptical nozzle, and also this corrugated nozzle. 271 00:14:40,000 --> 00:14:43,000 Oh, now, this reminds me of a flower with petals. 272 00:14:43,000 --> 00:14:45,000 I see what you mean. 273 00:14:45,000 --> 00:14:47,000 But in fact, they're called lobes. 274 00:14:47,000 --> 00:14:48,000 Lobes. 275 00:14:48,000 --> 00:14:49,000 Yes. 276 00:14:49,000 --> 00:14:55,000 And also we may change the round nozzle and how it looks by adding tabs at the ends that you see here. 277 00:14:55,000 --> 00:14:58,000 Oh, now, these tabs look like shark teeth. 278 00:14:58,000 --> 00:15:00,000 What other ways do you have to reduce noise? 279 00:15:00,000 --> 00:15:04,000 Well, Shelly, we use materials to line the inside of the nozzle. 280 00:15:07,000 --> 00:15:14,000 You see, this is called a liner, and what it's used to do is to absorb the sound before it exits the nozzle. 281 00:15:14,000 --> 00:15:15,000 Hmm, like a muffler. 282 00:15:15,000 --> 00:15:16,000 Yes. 283 00:15:16,000 --> 00:15:17,000 Okay, let's go back to Van now. 284 00:15:17,000 --> 00:15:22,000 What one point might you make back to Van that could help him with his problem? 285 00:15:23,000 --> 00:15:28,000 Hmm, I recommend that he buy ceiling tiles to line the ceiling of his garage. 286 00:15:28,000 --> 00:15:29,000 Oh, okay. 287 00:15:29,000 --> 00:15:34,000 And, Shelly, he can install carpet on the floor and draperies on the windows to help reduce the sound. 288 00:15:34,000 --> 00:15:39,000 Oh, Rich and Martha, that's great sound advice, and I will share that back with Van. 289 00:15:39,000 --> 00:15:40,000 Thank you so much. 290 00:15:40,000 --> 00:15:41,000 You're very welcome. 291 00:15:41,000 --> 00:15:46,000 All right, and to the rest of you, gang, I'm going to send you to find Van and see what he's up to. 292 00:15:46,000 --> 00:15:50,000 Meanwhile, I'm going to head back to the NASA Connect studio and get ready for our special guest. 293 00:15:50,000 --> 00:15:55,000 And if you haven't thought of some questions, think about some, because in a moment, you'll be able to call in with your questions. 294 00:15:55,000 --> 00:15:57,000 I'll see you back at the studio. 295 00:15:59,000 --> 00:16:05,000 Well, while I get things arranged with my band, the Noodles, I'm going to send you to Ruffner Middle School in Norfolk, Virginia, 296 00:16:05,000 --> 00:16:11,000 where you'll see students from the classroom of science teacher Ms. Susan Begay and math teacher Mr. Stephen Davis. 297 00:16:11,000 --> 00:16:15,000 They're conducting an experiment examining the speed of sound. 298 00:16:15,000 --> 00:16:20,000 Follow along, and after that, you can make your own analysis and predictions based upon their results. 299 00:16:20,000 --> 00:16:22,000 So I'll catch you all later. 300 00:16:24,000 --> 00:16:30,000 Hi, we're students from Ruffner Middle School in Norfolk, Virginia. 301 00:16:30,000 --> 00:16:38,000 NASA Connect asked us to investigate how sound waves travel at different speeds under various conditions. 302 00:16:38,000 --> 00:16:49,000 In this project, we'll be measuring the speed of sound and calculating the percentage of error with our science teacher Ms. Begay and our math and science teacher Mr. Davis. 303 00:16:49,000 --> 00:16:56,000 To prepare the experiment, pour one or two tablespoons of powdered sugar onto the middle of four sheets of tissue paper. 304 00:16:56,000 --> 00:16:59,000 Pull up the corners and tie it with string. 305 00:16:59,000 --> 00:17:05,000 Make four bags for the experiment and two additional bags in case of accidental breakage. 306 00:17:05,000 --> 00:17:07,000 Now we're ready to go. 307 00:17:07,000 --> 00:17:13,000 First, we record the wind direction, weather conditions, and outdoor temperature in Celsius. 308 00:17:13,000 --> 00:17:17,000 Next, we mark the spot where the sound engineer will hit the pots. 309 00:17:17,000 --> 00:17:21,000 From this point, we measure our 50-meter intervals. 310 00:17:21,000 --> 00:17:26,000 The linear speed engineer teams are located at each of these intervals. 311 00:17:26,000 --> 00:17:33,000 The sound assistants hold up the bulletin board paper to create a dark background behind the sound engineer, 312 00:17:34,000 --> 00:17:36,000 to see the puff of smoke. 313 00:17:36,000 --> 00:17:41,000 The sound engineer tapes one of the bags of powder to the middle bottom of the pan. 314 00:17:41,000 --> 00:17:46,000 When the sound person hits the two pans together, bursting the bag of powder, 315 00:17:46,000 --> 00:17:54,000 the linear speed engineers start their stopwatches at the first sign of smoke and to stop them as soon as they hear a sound. 316 00:17:54,000 --> 00:17:58,000 Warning, be ready to use a quick reaction time. 317 00:17:58,000 --> 00:18:02,000 Ready, set, go. 318 00:18:02,000 --> 00:18:07,000 The experiment is performed at least three times to get a range of data. 319 00:18:07,000 --> 00:18:11,000 Now we return to the classroom to analyze data. 320 00:18:11,000 --> 00:18:15,000 Mr. Davis gives us the formula for determining the speed of sound. 321 00:18:15,000 --> 00:18:18,000 Speed equals distance divided by time. 322 00:18:18,000 --> 00:18:23,000 Using the data collected, we calculate the speed of the sound at each location. 323 00:18:23,000 --> 00:18:26,000 We compare results between the locations. 324 00:18:26,000 --> 00:18:30,000 Mr. Davis asks, what do these numbers represent? 325 00:18:30,000 --> 00:18:37,000 Next, each group calculates the accepted value for the speed of sound at the recorded outside temperature. 326 00:18:37,000 --> 00:18:43,000 After we've posted our results, Mr. Davis asks us to calculate the percentage of error in the experiment 327 00:18:43,000 --> 00:18:50,000 using the following formula of amount of error divided by the accepted value times 100. 328 00:18:50,000 --> 00:18:53,000 We had a good time applying math to solve a problem. 329 00:18:55,000 --> 00:18:58,000 All right, welcome to the NASA Connect studio. 330 00:18:58,000 --> 00:19:02,000 Now joining me in the studio are Rich Silcox, a senior research scientist, 331 00:19:02,000 --> 00:19:07,000 and we're also now joined by Dennis Huff from NASA Glenn Research Center in Cleveland, Ohio. 332 00:19:07,000 --> 00:19:11,000 But before we talk to our researchers, let's give you a chance to do some analyzing 333 00:19:11,000 --> 00:19:14,000 using the data from the experiment you just saw. 334 00:19:14,000 --> 00:19:18,000 After this segment, our two researchers will be answering your e-mail questions 335 00:19:18,000 --> 00:19:21,000 and taking questions from the viewing audience. 336 00:19:21,000 --> 00:19:25,000 Okay now, look carefully at the data and using the information in the following diagram, 337 00:19:25,000 --> 00:19:30,000 work with your fellow students to answer the questions as read aloud by Rich Silcox. 338 00:19:32,000 --> 00:19:37,000 As the distance increased from 50 meters, what happened to the mean time? 339 00:19:55,000 --> 00:20:14,000 Music 340 00:20:14,000 --> 00:20:22,000 Use the formula percent of experimental error equals calculated value minus accepted value 341 00:20:22,000 --> 00:20:31,000 divided by the accepted value times 100 to calculate the percentage of error at 50 meters and 300 meters. 342 00:20:31,000 --> 00:20:33,000 Why do you think they are different? 343 00:20:33,000 --> 00:20:54,000 Music 344 00:20:54,000 --> 00:20:57,000 The speed of sound is directly proportional to air temperature. 345 00:20:57,000 --> 00:21:02,000 Is the speed of sound faster in the summer or winter? Why? 346 00:21:02,000 --> 00:21:31,000 Music 347 00:21:32,000 --> 00:21:34,000 All right, we're back. 348 00:21:34,000 --> 00:21:37,000 And with me are Rich Silcox and Dennis Huff to answer your questions. 349 00:21:37,000 --> 00:21:42,000 But let's start things off by asking Dennis, what is it, Dennis, that you actually do there at NASA Glenn? 350 00:21:42,000 --> 00:21:43,000 I'd be glad to answer that. 351 00:21:43,000 --> 00:21:45,000 Hello, my name is Dennis Huff. 352 00:21:45,000 --> 00:21:48,000 I'm the Chief of the Acoustics Branch at NASA's Glenn Research Center. 353 00:21:48,000 --> 00:21:50,000 It's located in Cleveland, Ohio. 354 00:21:50,000 --> 00:21:54,000 Our contribution to quieting the skies looks at ways to making the engines quieter. 355 00:21:54,000 --> 00:21:57,000 Our goal is to develop engine noise reduction technology 356 00:21:57,000 --> 00:22:01,000 without compromising the engine performance or the aircraft's safety. 357 00:22:01,000 --> 00:22:06,000 Some members of our team develop mathematical models to be able to predict the sound from the engine, 358 00:22:06,000 --> 00:22:11,000 while others test different parts of the engine inside wind tunnels and anechoic chambers. 359 00:22:11,000 --> 00:22:14,000 Our best noise reduction concepts will eventually be tested on engines 360 00:22:14,000 --> 00:22:17,000 to make sure that we can really make the airplanes quieter. 361 00:22:17,000 --> 00:22:21,000 You've got a lot of good stuff going there that I could ask a lot of questions about. 362 00:22:21,000 --> 00:22:23,000 And I just might do that, Dennis. 363 00:22:23,000 --> 00:22:26,000 But I've got some e-mail questions that have come in for both you guys. 364 00:22:26,000 --> 00:22:28,000 So let me start with an e-mail question. 365 00:22:28,000 --> 00:22:33,000 The first question is, does the shape of a plane affect the sound? 366 00:22:33,000 --> 00:22:36,000 And this is from Jonathan in Virginia Beach. 367 00:22:36,000 --> 00:22:41,000 Yeah, Shelley, the shape of the airplane does change the sound dramatically. 368 00:22:41,000 --> 00:22:44,000 For instance, when the airplane is coming in for a landing or taking off, 369 00:22:44,000 --> 00:22:48,000 the flaps in the landing gear are deployed. 370 00:22:48,000 --> 00:22:51,000 In that case, the flow is very dirty and it makes a lot more noise 371 00:22:51,000 --> 00:22:55,000 than when those components are stowed away. 372 00:22:55,000 --> 00:22:58,000 Yes, and in fact, it's interesting on the engine itself. 373 00:22:58,000 --> 00:23:02,000 You'll notice that some of the older aircraft have smaller diameter engines. 374 00:23:02,000 --> 00:23:06,000 And the smaller diameter actually passes a lot more flow at a higher velocity, 375 00:23:06,000 --> 00:23:09,000 and this causes the jet noise to be very loud. 376 00:23:09,000 --> 00:23:13,000 We have a general rule of thumb that we say that the exit of the velocity 377 00:23:13,000 --> 00:23:16,000 raised to the eighth power is proportional to the jet noise. 378 00:23:16,000 --> 00:23:21,000 So the newer aircraft that have larger diameter engines actually end up being quieter. 379 00:23:21,000 --> 00:23:23,000 All right, and let's go back to this. 380 00:23:23,000 --> 00:23:26,000 I kind of answered this already, but I'm thinking about me who flies an awful lot 381 00:23:26,000 --> 00:23:30,000 on these small little, they call them puddle jumpers or commuter planes 382 00:23:30,000 --> 00:23:34,000 compared to your bigger 757s. 383 00:23:34,000 --> 00:23:38,000 How is there a difference on those size of engines 384 00:23:38,000 --> 00:23:41,000 and the noise that they are generating? 385 00:23:41,000 --> 00:23:43,000 Sure, those engines are some of the newer engines. 386 00:23:43,000 --> 00:23:45,000 We call those higher bypass ratio engines. 387 00:23:45,000 --> 00:23:47,000 And so you've got a lot of flow going through that. 388 00:23:47,000 --> 00:23:50,000 It's a lot of thrust in that engine, but it's going at a lower velocity, 389 00:23:50,000 --> 00:23:52,000 so it's a much quieter engine than the older ones. 390 00:23:52,000 --> 00:23:54,000 Oh, okay. 391 00:23:54,000 --> 00:23:57,000 In a lot of cases, the propeller airplanes are quieter too. 392 00:23:57,000 --> 00:23:59,000 They're quieter than the large jets are. 393 00:23:59,000 --> 00:24:01,000 All right, I've got a question. 394 00:24:01,000 --> 00:24:05,000 You keep talking about research to reduce noise around communities. 395 00:24:05,000 --> 00:24:09,000 What is the community that you all are referring to here? 396 00:24:09,000 --> 00:24:12,000 Well, generally we're talking about that area around the airport 397 00:24:12,000 --> 00:24:16,000 that's affected by the operations of the airplanes taking off and landing. 398 00:24:16,000 --> 00:24:18,000 Once the airplane climbs to altitude, 399 00:24:18,000 --> 00:24:22,000 is it cruise altitude maybe at 35,000 feet? 400 00:24:22,000 --> 00:24:24,000 You don't really hear it much anymore. 401 00:24:24,000 --> 00:24:26,000 Okay, all right, good. 402 00:24:26,000 --> 00:24:28,000 Well, I've got someone telling me we've got a caller out there, 403 00:24:28,000 --> 00:24:30,000 so let's go ahead and take that caller. 404 00:24:30,000 --> 00:24:34,000 Caller, could I have your first name, please, and your question? 405 00:24:34,000 --> 00:24:40,000 My name is Timothy, and my question is 406 00:24:40,000 --> 00:24:49,000 how fast is the sound travels through water? 407 00:24:49,000 --> 00:24:53,000 Oh, okay, the sound traveling through water. 408 00:24:53,000 --> 00:24:57,000 And is there a difference between the speed that sound travels in air and water? 409 00:24:57,000 --> 00:25:02,000 Yes, the speed travels through water much more quickly than it does in air. 410 00:25:02,000 --> 00:25:04,000 I can't recall the exact number. 411 00:25:04,000 --> 00:25:08,000 I think it's three or four times faster in water than it is in air. 412 00:25:08,000 --> 00:25:13,000 Okay, all right, so we know that it is going to travel faster through water than in air. 413 00:25:13,000 --> 00:25:15,000 Good question there, Timothy. 414 00:25:15,000 --> 00:25:18,000 I'm going to take a final question I have here by e-mail. 415 00:25:18,000 --> 00:25:21,000 Very quickly, well, no, final advice. 416 00:25:21,000 --> 00:25:25,000 What advice would you, Dennis, give to viewers about thinking about careers? 417 00:25:25,000 --> 00:25:26,000 I'd be glad to answer that. 418 00:25:26,000 --> 00:25:28,000 My father gave me the advice to keep your options open. 419 00:25:28,000 --> 00:25:30,000 You can get into a lot of different activities 420 00:25:30,000 --> 00:25:33,000 and make sure you involve yourself in extracurricular activities 421 00:25:33,000 --> 00:25:36,000 but also stay with your math and science and your English. 422 00:25:36,000 --> 00:25:38,000 Different courses are very important. 423 00:25:38,000 --> 00:25:40,000 All right, there you've heard it from us. 424 00:25:40,000 --> 00:25:42,000 And I see we're quickly running out of time. 425 00:25:42,000 --> 00:25:44,000 Thank you, Dennis and Rich. 426 00:25:44,000 --> 00:25:48,000 And now students from Jonas Clark Middle School in Lexington, Massachusetts, 427 00:25:48,000 --> 00:25:52,000 share some technology notes that are sure to sharpen your investigation on sound 428 00:25:52,000 --> 00:25:54,000 following this program. 429 00:25:57,000 --> 00:26:01,000 One part of the website is called the NASA Sound Machine. 430 00:26:01,000 --> 00:26:05,000 With it, you'll learn about the shapes and characteristics of sound waves, 431 00:26:05,000 --> 00:26:07,000 how an airplane produces different kinds of noise, 432 00:26:07,000 --> 00:26:11,000 and what some words would sound like if you had severe or partial hearing loss. 433 00:26:11,000 --> 00:26:15,000 Another part of the NASA Connect website features NASA researchers 434 00:26:15,000 --> 00:26:17,000 talking about their jobs. 435 00:26:17,000 --> 00:26:19,000 It's called Career Corner. 436 00:26:19,000 --> 00:26:23,000 There's also a fun quiz that will test your knowledge of sound and hearing. 437 00:26:23,000 --> 00:26:28,000 Hey, a big thanks now to our Jonas Clark Middle School for that technology tease. 438 00:26:28,000 --> 00:26:32,000 And thank you to all our program guests and partners. 439 00:26:32,000 --> 00:26:36,000 If you wish a videotaped copy of this NASA Connect show and lesson plans, 440 00:26:36,000 --> 00:26:41,000 then contact CORE, the NASA Central Operation of Resources for Educators. 441 00:26:41,000 --> 00:26:45,000 Well, gang, that's it for this season of NASA Connect. 442 00:26:45,000 --> 00:26:48,000 But join us again next season for more NASA Connect programs, 443 00:26:48,000 --> 00:26:50,000 math, science, and researchers. 444 00:26:50,000 --> 00:26:53,000 And, of course, for more of Van and me, 445 00:26:53,000 --> 00:26:56,000 I'll be joining you from our nation's capital, Washington, D.C., 446 00:26:56,000 --> 00:26:59,000 as a special correspondent to NASA Connect. 447 00:26:59,000 --> 00:27:04,000 Let's do a final sound check on Van as he professionally records his song. 448 00:27:04,000 --> 00:27:07,000 Okay. I think we have something pretty good for you, Shelley. 449 00:27:07,000 --> 00:27:10,000 Ready, guys? Hit it. 450 00:27:10,000 --> 00:27:16,000 ♪♪♪ 451 00:27:16,000 --> 00:27:24,000 ♪♪ Follow your heart, pursue your dream. 452 00:27:24,000 --> 00:27:32,000 But when you set out on some new scheme, 453 00:27:32,000 --> 00:27:36,000 look all around, know what's out there. 454 00:27:36,000 --> 00:27:42,000 Connect your feelings and goals with care to reach your star. 455 00:27:42,000 --> 00:27:46,000 Connect with who you are. 456 00:27:46,000 --> 00:27:52,000 ♪♪♪ 457 00:27:52,000 --> 00:28:00,000 ♪ Know where you're going, know where you've been. 458 00:28:00,000 --> 00:28:08,000 Look to the future to help you win. 459 00:28:08,000 --> 00:28:12,000 Know what's inside, know what's out there. 460 00:28:12,000 --> 00:28:18,000 Connect your feelings and goals with care to reach your star. 461 00:28:18,000 --> 00:28:22,000 Connect with who you are. 462 00:28:22,000 --> 00:28:26,000 ♪♪♪ 463 00:28:26,000 --> 00:28:31,000 Connect with who you are.