1 00:00:00,000 --> 00:00:07,680 Boys and girls, this is Dr. D. He's brought something really special to share with us 2 00:00:07,680 --> 00:00:08,680 today. 3 00:00:08,680 --> 00:00:09,680 Good morning. 4 00:00:09,680 --> 00:00:10,680 Good morning. 5 00:00:10,680 --> 00:00:12,720 I already have an experiment set up. 6 00:00:12,720 --> 00:00:16,120 It's going to show you the difference between high and low frequency sounds. 7 00:00:16,120 --> 00:00:18,400 Will we be able to see anything? 8 00:00:18,400 --> 00:00:19,960 Not once you'll be able to hear it. 9 00:00:19,960 --> 00:00:22,600 This machine is going to produce sounds at different frequencies. 10 00:00:22,600 --> 00:00:26,080 I want you to raise your hand when you can't hear the sound anymore. 11 00:00:26,560 --> 00:00:30,640 It's just going to give you an idea by high and low frequency sounds. 12 00:00:30,640 --> 00:00:31,640 Here we go. 13 00:00:49,160 --> 00:00:51,120 Oh, looks like we lost your teacher first. 14 00:00:51,120 --> 00:00:52,120 I can't hear it either. 15 00:00:52,120 --> 00:00:55,320 When you get older, you can't hear high frequency sounds as well. 16 00:00:55,320 --> 00:00:56,320 Let's keep going. 17 00:01:02,600 --> 00:01:04,600 Ah, no one can hear it now. 18 00:01:04,600 --> 00:01:07,160 I bet your dogs can still hear it. 19 00:01:07,160 --> 00:01:09,440 Now we'll need some volunteers. 20 00:01:09,440 --> 00:01:13,640 I'll take you and you and you and you. 21 00:01:15,760 --> 00:01:19,040 I'm going to transmit a low frequency sound to you. 22 00:01:19,040 --> 00:01:23,280 PJ's going to put the phone between the speaker and your ear a couple of times. 23 00:01:23,280 --> 00:01:24,280 Let's do it. 24 00:01:25,320 --> 00:01:26,320 What happened? 25 00:01:26,320 --> 00:01:27,320 The sound wasn't as loud. 26 00:01:27,320 --> 00:01:28,320 Now I'm going to transmit a higher frequency sound. 27 00:01:28,320 --> 00:01:29,320 What happened this time? 28 00:01:29,320 --> 00:01:30,320 It seemed like the sound was blocked off a lot more. 29 00:01:30,320 --> 00:01:31,320 Let's try it again. 30 00:01:31,320 --> 00:01:32,320 Why don't you two switch places? 31 00:01:32,320 --> 00:01:33,320 Okay. 32 00:01:33,320 --> 00:01:34,320 Okay. 33 00:01:34,320 --> 00:01:35,320 Okay. 34 00:01:35,320 --> 00:01:36,320 Okay. 35 00:01:36,320 --> 00:01:37,320 Okay. 36 00:01:37,320 --> 00:01:38,320 Okay. 37 00:01:38,320 --> 00:01:39,320 Okay. 38 00:01:39,320 --> 00:01:40,320 Okay. 39 00:01:40,320 --> 00:01:41,320 Okay. 40 00:01:41,320 --> 00:01:42,320 Okay. 41 00:01:42,320 --> 00:01:43,320 Okay. 42 00:01:43,320 --> 00:01:44,320 Okay. 43 00:01:44,320 --> 00:01:45,320 Okay. 44 00:01:45,320 --> 00:01:46,320 Okay. 45 00:01:46,320 --> 00:01:47,320 Okay. 46 00:01:47,320 --> 00:01:48,320 Okay. 47 00:01:48,320 --> 00:01:49,320 Okay. 48 00:01:49,320 --> 00:01:50,320 Okay. 49 00:01:50,320 --> 00:01:51,320 Okay. 50 00:01:51,320 --> 00:01:52,320 Okay. 51 00:01:52,320 --> 00:01:53,320 Okay. 52 00:01:53,320 --> 00:01:54,320 Okay. 53 00:01:55,320 --> 00:01:56,320 Okay. 54 00:01:56,320 --> 00:01:57,320 Okay. 55 00:01:57,320 --> 00:01:58,320 Okay. 56 00:01:58,320 --> 00:01:59,320 Okay. 57 00:01:59,320 --> 00:02:00,320 Okay. 58 00:02:03,320 --> 00:02:04,320 Okay. 59 00:02:10,320 --> 00:02:12,320 Okay. 60 00:02:12,320 --> 00:02:13,320 Okay. 61 00:02:13,320 --> 00:02:15,320 Okay. 62 00:02:18,320 --> 00:02:20,320 Okay. 63 00:02:20,320 --> 00:02:21,320 Okay. 64 00:02:21,320 --> 00:02:22,320 Okay. 65 00:02:22,320 --> 00:02:23,320 It became a little bit softer. 66 00:02:24,320 --> 00:02:27,320 The book was the same distance both times. 67 00:02:27,320 --> 00:02:29,320 Remember, with the scientific method, 68 00:02:29,320 --> 00:02:32,320 you can only change one variable at a time. 69 00:02:32,320 --> 00:02:33,320 I changed the frequency, 70 00:02:33,320 --> 00:02:37,320 so I'm glad Jacob was careful to keep the book distance the same both times. 71 00:02:37,320 --> 00:02:41,320 I think that low-frequency sounds travel better than high-frequency sounds. 72 00:02:41,320 --> 00:02:46,320 Well, low-frequency sounds do bend around corners a lot easier than high-frequency sounds. 73 00:02:46,320 --> 00:02:49,320 That's why the lower-frequency sound was a little clearer, 74 00:02:49,320 --> 00:02:51,320 because it bent around the phone book. 75 00:02:51,320 --> 00:02:53,320 This is so cool! 76 00:02:53,320 --> 00:02:57,320 This experiment taught us that high-frequency sounds don't bend around corners very easily. 77 00:02:57,320 --> 00:02:59,320 Don't forget what we learned about the bats. 78 00:02:59,320 --> 00:03:01,320 How could we forget? 79 00:03:01,320 --> 00:03:04,320 High-frequency bat calls don't travel very far. 80 00:03:04,320 --> 00:03:06,320 What does all this mean? 81 00:03:06,320 --> 00:03:09,320 Let's go back to our treehouse after school and think about it.