1 00:00:00,000 --> 00:00:02,000 Too bad PJ couldn't make it. 2 00:00:02,000 --> 00:00:05,000 Look, what or who is that? 3 00:00:05,000 --> 00:00:07,000 Oh, that's Fred the Head. 4 00:00:07,000 --> 00:00:09,000 You must be the treehouse detectives. 5 00:00:09,000 --> 00:00:11,000 I'm Bianca, and this is Jacob. 6 00:00:11,000 --> 00:00:13,000 We're trying to solve a really big problem. 7 00:00:13,000 --> 00:00:16,000 Dogs are barking and keeping us up at night and in the early morning. 8 00:00:16,000 --> 00:00:18,000 I heard about that on the news. 9 00:00:18,000 --> 00:00:21,000 We think that a really loud sound might be making them bark. 10 00:00:21,000 --> 00:00:23,000 We're researching sound. 11 00:00:23,000 --> 00:00:26,000 We'd like to learn how you deal with sound problems. 12 00:00:26,000 --> 00:00:29,000 Well, I'm a psychoacoustician here at Nassau Langley Research Center. 13 00:00:29,000 --> 00:00:31,000 That's a really big word. 14 00:00:31,000 --> 00:00:33,000 I don't think I can even say that. 15 00:00:33,000 --> 00:00:35,000 So what do you do here? 16 00:00:35,000 --> 00:00:39,000 Well, as a psychoacoustician, I design, conduct and analyze tests 17 00:00:39,000 --> 00:00:42,000 and investigate the psychological effects of noise on people. 18 00:00:42,000 --> 00:00:45,000 Let me show you one of my labs. 19 00:00:45,000 --> 00:00:47,000 Is this a real plane? 20 00:00:47,000 --> 00:00:49,000 No, this is a fake. 21 00:00:49,000 --> 00:00:51,000 But we go up in real planes and we make recordings 22 00:00:51,000 --> 00:00:53,000 and we bring them down to the lab and we modify them. 23 00:00:53,000 --> 00:00:55,000 Then we can play them back to people in here 24 00:00:55,000 --> 00:00:58,000 and find out which kind of sounds they prefer. 25 00:00:58,000 --> 00:01:00,000 So what kind of sounds do people prefer? 26 00:01:00,000 --> 00:01:02,000 Well, quiet ones really. 27 00:01:02,000 --> 00:01:07,000 We hear from 20 vibrations per second to 20,000 vibrations per second. 28 00:01:07,000 --> 00:01:11,000 And the low frequency ones bother us less than the high frequencies. 29 00:01:11,000 --> 00:01:15,000 For instance, have you heard a piece of chalk scratching on a chalkboard? 30 00:01:15,000 --> 00:01:16,000 Yuck! 31 00:01:16,000 --> 00:01:17,000 Well, that's a high frequency sound. 32 00:01:17,000 --> 00:01:20,000 What about dogs? Do they hear differently from us? 33 00:01:20,000 --> 00:01:24,000 Well, I'm not an expert on dogs, but I know dogs can hear higher frequencies than we do. 34 00:01:24,000 --> 00:01:26,000 They can hear very high frequencies. 35 00:01:26,000 --> 00:01:27,000 Come on, let's go. 36 00:01:31,000 --> 00:01:35,000 So, we need to find out what kind of things make very high frequency noises. 37 00:01:35,000 --> 00:01:37,000 What about a machine or a factory? 38 00:01:37,000 --> 00:01:39,000 They both might be possibilities. 39 00:01:39,000 --> 00:01:42,000 That could be it. It could be a noise from a nearby factory. 40 00:01:42,000 --> 00:01:43,000 We might have the answer. 41 00:01:43,000 --> 00:01:45,000 You mean the hypothesis. 42 00:01:45,000 --> 00:01:48,000 You need to go and talk to my friend veterinarian. 43 00:01:48,000 --> 00:01:49,000 His name's Dr. Gooding. 44 00:01:49,000 --> 00:01:52,000 Oh, here he is. He's right around the corner. 45 00:01:52,000 --> 00:01:54,000 Great. I love going to pet hospitals. 46 00:01:54,000 --> 00:01:56,000 I'll call my parents and see if it's okay. 47 00:01:57,000 --> 00:02:00,000 I wonder what kind of neat pets we will see today. 48 00:02:00,000 --> 00:02:03,000 Hi, we're the Treehouse Detectives. We're here to see Dr. Gooding. 49 00:02:03,000 --> 00:02:05,000 Please come this way. How can I help you? 50 00:02:10,000 --> 00:02:13,000 Thanks for helping us. I'm Jacob, and this is Bianca. 51 00:02:13,000 --> 00:02:16,000 Have you heard about the dog barking problem on KSNN? 52 00:02:16,000 --> 00:02:20,000 Yes, I have. I know it's keeping a lot of people up at night. 53 00:02:20,000 --> 00:02:21,000 Tell me about it. 54 00:02:21,000 --> 00:02:24,000 We need to know dogs hear sounds differently from us. 55 00:02:25,000 --> 00:02:29,000 Whoa, look at that big dog. I know he can hear us. 56 00:02:30,000 --> 00:02:34,000 Yes, dogs tend to hear at a much higher frequency than human beings. 57 00:02:34,000 --> 00:02:38,000 This means they can hear sounds that the human ear cannot hear. 58 00:02:38,000 --> 00:02:43,000 Dogs can hear sounds between 67 Hz and 45 kHz. 59 00:02:43,000 --> 00:02:47,000 Now, people can only hear between 20 Hz and 20 kHz. 60 00:02:47,000 --> 00:02:50,000 Do the insides of dogs' ears look like ours? 61 00:02:50,000 --> 00:02:51,000 What? 62 00:02:51,000 --> 00:02:56,000 That's actually a good question. I have something to show you. Let's go, guys. 63 00:02:59,000 --> 00:03:01,000 Let's take a look at Millie's ears. 64 00:03:02,000 --> 00:03:06,000 Actually, the anatomy of the human ear is similar to that of the dog. 65 00:03:06,000 --> 00:03:09,000 Those are actual pictures of Millie's ears. 66 00:03:09,000 --> 00:03:14,000 However, dogs have some equipment or parts that might have better hearing. 67 00:03:14,000 --> 00:03:22,000 For example, dogs tend to have a long ear canal that might allow sound to be funneled or directed into the hearing apparatus. 68 00:03:22,000 --> 00:03:29,000 It's a lot like this funnel, something that is used to direct water into this bottle so that you don't spill it. 69 00:03:37,000 --> 00:03:41,000 So that's why dogs can hear noises at higher frequencies. 70 00:03:41,000 --> 00:03:43,000 They can hear things that we can't. 71 00:03:43,000 --> 00:03:48,000 That's true. Dogs used to be wild before they were domesticated. 72 00:03:48,000 --> 00:03:52,000 They had to survive by finding food and escaping predators. 73 00:03:52,000 --> 00:03:56,000 Therefore, they might have had to depend on their ears to survive. 74 00:03:56,000 --> 00:04:00,000 That's cool. Dr. Gooding, do you know any good examples of high-frequency sounds? 75 00:04:00,000 --> 00:04:06,000 Hmm, let's see. Are you familiar with dog whistles or pest zappers? 76 00:04:06,000 --> 00:04:09,000 These are good examples of high-frequency sounds. 77 00:04:09,000 --> 00:04:12,000 Thanks, doctor, for all your information. 78 00:04:12,000 --> 00:04:13,000 We'll see you later.