WEBVTT - TechStuff Classic: Shh! How Soundproofing Works 0:00:04.440 --> 0:00:12.440 Welcome to tech Stuff, a production from iHeartRadio. Pay there 0:00:12.480 --> 0:00:15.880 and welcome to tech Stuff. I'm your host, Jonathan Strickland. 0:00:15.920 --> 0:00:19.360 I'm an executive producer with iHeartRadio and how the tech 0:00:19.400 --> 0:00:22.599 are you? It is time for a classic episode of 0:00:22.640 --> 0:00:28.040 tech Stuff. This episode originally published on June first, twenty sixteen, 0:00:28.400 --> 0:00:33.480 and it is titled SSH How Soundproofing Works. And Noel 0:00:33.680 --> 0:00:39.160 Brown now an incredible executive producer, a host of ridiculous history, 0:00:39.200 --> 0:00:40.839 a host of stuff they don't want you to know. 0:00:42.000 --> 0:00:46.599 Back then he was a producer, but like a supervising producer. 0:00:46.680 --> 0:00:49.760 Now he wears so many hats which we get to 0:00:49.760 --> 0:00:52.920 see whenever he's on one of our all hands meetings. 0:00:53.960 --> 0:00:56.920 He joined the show to talk about how soundproofing works. 0:00:57.000 --> 0:01:01.640 So enjoy this classic episode. So one of the things 0:01:01.680 --> 0:01:03.040 I like to do on the show is at the 0:01:03.120 --> 0:01:06.240 end of every episode, I invite you guys to send 0:01:06.280 --> 0:01:12.080 me requests, ideas topics for future episodes. And today's episode 0:01:12.360 --> 0:01:15.240 is due to that. So I'm going to read a 0:01:15.280 --> 0:01:21.840 little bit of listener. May dude, we used to have 0:01:21.840 --> 0:01:24.640 a whole Clackson all right, here he goes, Hey you 0:01:24.760 --> 0:01:27.000 tech Stuff. First off, I want to thank you for 0:01:27.040 --> 0:01:29.440 putting out your content as I'm a huge fan of 0:01:29.440 --> 0:01:32.480 this casual learning movement. Might need a better term for that. 0:01:32.880 --> 0:01:35.039 I was wondering if you'd be able to do an 0:01:35.040 --> 0:01:38.920 episode on acoustics and sound dampening for studios, like how 0:01:38.959 --> 0:01:42.160 they're measured, tuned, made, et cetera. It would be awesome 0:01:42.200 --> 0:01:44.800 and spectacular as I would be able to harness the 0:01:44.840 --> 0:01:47.760 power to put together a kick ass setup. Thanks again 0:01:47.760 --> 0:01:52.800 for what you do. Dubnosis well dubbed, We're going to 0:01:52.880 --> 0:01:54.920 do that for you. And that's really the reason why 0:01:54.920 --> 0:01:57.480 I asked Noel to come in here, because Noel, as 0:01:57.560 --> 0:02:01.919 a producer and sound engineer type person, has had real 0:02:02.080 --> 0:02:05.680 world experience with this, and so we're going to rely 0:02:05.800 --> 0:02:10.160 heavily upon his perspective some of the stories he has 0:02:10.200 --> 0:02:12.840 to tell about the process of trying to make a 0:02:13.000 --> 0:02:17.119 room more soundproof or tuning a room so that you're 0:02:17.160 --> 0:02:20.359 getting the sound you want while you're recording, Because, as 0:02:20.360 --> 0:02:23.440 it turns out, sound is a pretty tricky thing when 0:02:23.480 --> 0:02:28.160 you boil it down. Sound is vibration, right, It's just 0:02:28.400 --> 0:02:33.160 particles banging together. It is a thing you gotta wrangle. 0:02:33.760 --> 0:02:37.760 We often consider sound to just be this thing we 0:02:37.880 --> 0:02:41.040 perceive with our ears. But what's really happening is a 0:02:41.040 --> 0:02:46.360 little more granular than that. Sound is particles that are vibrating. 0:02:47.480 --> 0:02:51.160 Typically we're hearing things that are coming through over the air, 0:02:51.520 --> 0:02:55.000 like actual air around us. So you listening to this 0:02:55.120 --> 0:02:59.040 right now, you can hear my voice. Well, what's actually 0:02:59.040 --> 0:03:03.239 happening is that some are vibrating some air molecules, and 0:03:03.320 --> 0:03:08.440 that is compressing and decompressing those molecules. It's changing the pressure, 0:03:08.560 --> 0:03:13.120 increasing and then decreasing the pressure at frequencies and amplitudes 0:03:13.120 --> 0:03:16.120 that your ears pick up and then you perceive a sound. 0:03:16.360 --> 0:03:19.880 So this is happening through all sorts of media, not 0:03:20.040 --> 0:03:22.280 just air. It can pass through solid matter, it can 0:03:22.320 --> 0:03:25.120 pass through liquid and depending on how the particles are 0:03:25.160 --> 0:03:28.079 packed and the space between them, sound may move better 0:03:28.120 --> 0:03:33.160 through one medium than through another. Now, knowing that sound 0:03:33.200 --> 0:03:35.960 can travel through different media, you also need to know 0:03:36.000 --> 0:03:40.120 that it can transfer from one medium to another medium. So, 0:03:40.240 --> 0:03:44.080 for example, if I'm shouting really really loudly in a 0:03:44.120 --> 0:03:47.480 little room, some of that sound when it makes contact 0:03:47.480 --> 0:03:51.400 with the wall, actually causes the wall to move. Now, 0:03:51.400 --> 0:03:54.160 it's not causing the wall to move a lot, but 0:03:54.240 --> 0:03:56.480 it is making the wall vibrate a little bit, those 0:03:56.560 --> 0:04:00.120 vibrations get transferred through the wall to the other side, 0:04:00.240 --> 0:04:03.200 and that's why if you're in a place that has 0:04:03.520 --> 0:04:06.960 flimsy walls, you can hear someone in another room. The 0:04:06.960 --> 0:04:08.640 sound is actually transferring through. 0:04:08.680 --> 0:04:11.560 Not to mention in the room itself, that sound is 0:04:11.600 --> 0:04:14.080 actually reflecting back at you. And the quality of the 0:04:14.160 --> 0:04:17.640 sound can depend can vary greatly depending on the material 0:04:17.680 --> 0:04:19.560 that the room is built out of or treated with. 0:04:19.760 --> 0:04:23.080 Right right, So some of the sounds getting transferred through 0:04:23.120 --> 0:04:25.320 the material, some of the sound is being bounced back 0:04:25.360 --> 0:04:28.560 from the material towards you, and a lot of that 0:04:28.600 --> 0:04:32.400 depends upon the hardness of the material, Like a really 0:04:32.400 --> 0:04:34.400 hard material is going to bounce a lot more sound 0:04:34.480 --> 0:04:36.640 back at you, which is why if you are in 0:04:36.800 --> 0:04:39.599 a large room with a lot of hard surfaces you 0:04:39.640 --> 0:04:43.640 get that echoe sound. Or if you're out someplace like 0:04:44.120 --> 0:04:46.120 at a canyon and you do a shout and you 0:04:46.160 --> 0:04:48.760 get that echo back, it's because the sound is going 0:04:48.760 --> 0:04:52.680 out hitting the walls of the canyon, bouncing back to you, 0:04:53.000 --> 0:04:57.880 and that's when you get to experience that effect. Well, obviously, 0:04:58.520 --> 0:05:02.120 this means that if you want to create a place 0:05:02.839 --> 0:05:07.800 where the sound can't escape or leak into and a 0:05:07.839 --> 0:05:10.200 lot of recording studios, you want both of those things right. 0:05:10.200 --> 0:05:12.680 You don't want the sound from the studio to leak outward, 0:05:12.880 --> 0:05:15.400 but you also definitely don't want outside sound to leak 0:05:15.480 --> 0:05:18.840 in to the stereovery important then you have to figure out, well, 0:05:18.880 --> 0:05:21.200 how do we limit how do we work within the 0:05:21.240 --> 0:05:26.600 physical constraints of the way sound works, so that we 0:05:26.680 --> 0:05:29.280 can limit that as much as possible and try to 0:05:29.279 --> 0:05:35.520 have the purest experience as we can. So one thing 0:05:35.560 --> 0:05:38.880 you can remember is that sound, because it's a physical 0:05:39.160 --> 0:05:43.440 activity and because it relies on energy, the way it 0:05:43.480 --> 0:05:45.560 works is that you've got a source of the sound. 0:05:46.320 --> 0:05:51.400 Sound waves travel outward concentrically outward from that source, and 0:05:51.480 --> 0:05:54.479 they get weaker as they travel out that that energy 0:05:54.560 --> 0:05:56.720 starts to dissipate. You can think of it kind of 0:05:56.760 --> 0:06:00.480 like you know, each each time of part article has 0:06:00.520 --> 0:06:03.160 to bang up against another one to move it, some 0:06:03.240 --> 0:06:05.599 of that energy ends up getting lost. So the further 0:06:05.640 --> 0:06:07.440 way you are from a source of sound, the quieter 0:06:07.520 --> 0:06:10.279 it is. That's why that happens. So one way you 0:06:10.320 --> 0:06:13.560 can limit the way sound comes out of a room 0:06:13.640 --> 0:06:16.400 is you make an enormous room, like you have a 0:06:16.440 --> 0:06:20.800 little room in a really big room. But that's not 0:06:20.839 --> 0:06:22.760 necessarily the most practical approach. 0:06:22.920 --> 0:06:25.599 Actually, there's a studio I used to intern in Athens, 0:06:25.600 --> 0:06:29.440 Georgia called Chase Park Transduction, and they essentially built their 0:06:29.480 --> 0:06:33.600 studio inside of a larger warehouse space. So they're renting 0:06:33.640 --> 0:06:36.040 a space in the strip of big, giant, very high 0:06:36.040 --> 0:06:39.120 ceilin warehouse spaces. But when you go into the studio, 0:06:39.520 --> 0:06:43.720 you're in the warehouse. But then there's a smaller basically 0:06:43.880 --> 0:06:47.920 building inside that warehouse that is the one that receives 0:06:47.960 --> 0:06:50.520 all the acoustic treatments. But it's like you said, I 0:06:50.560 --> 0:06:53.000 mean that is one way of dealing with it is air. 0:06:53.360 --> 0:06:56.760 Yeah, the room within a room approach is often how 0:06:56.760 --> 0:06:59.880 it's referred to, and sometimes it is not as obvious 0:07:00.200 --> 0:07:02.600 that like it may be that it looks like the 0:07:04.200 --> 0:07:06.200 room you're walking into. It might be like it's it's 0:07:06.240 --> 0:07:10.080 in a little alcover hallway, but that hallway is actually 0:07:10.160 --> 0:07:13.280 showing where the walls are where there's an air gap 0:07:13.440 --> 0:07:17.240 between the two walls to mitigate any sound coming into 0:07:17.320 --> 0:07:17.800 the space. 0:07:17.880 --> 0:07:20.400 Sure, even this glass window that we have in the 0:07:20.440 --> 0:07:22.520 booth that we're recording in right now, it's a double 0:07:22.600 --> 0:07:26.240 paned window. So in between these two relatively thick pieces 0:07:26.240 --> 0:07:28.800 of glass is a little layer of air, which in 0:07:28.840 --> 0:07:30.880 and of itself acts as a bit of a sound 0:07:30.920 --> 0:07:32.440 dampening insulation device. 0:07:32.320 --> 0:07:35.960 Right exactly, So some other little elements of sound that 0:07:36.000 --> 0:07:40.480 we need to remember. There are two main components to 0:07:40.880 --> 0:07:43.320 a sound wave that are important to keep in mind. 0:07:43.320 --> 0:07:46.400 One is amplitude or volume. So if you are looking 0:07:46.480 --> 0:07:50.200 at the way we typically show a sound wave which 0:07:50.240 --> 0:07:53.080 is on like an X versus y graph, you know 0:07:53.120 --> 0:07:57.720 those those sine wave style graphs, the height and depth 0:07:57.760 --> 0:08:00.920 of the troughs that represents the amplitude how out the 0:08:01.000 --> 0:08:03.680 sound is. Then you have the frequency of sound, the 0:08:03.800 --> 0:08:08.560 number of times sound cycles within a second. That determines 0:08:08.600 --> 0:08:10.360 the pitch of a sound. 0:08:10.520 --> 0:08:14.520 So a low frequency, obviously would be a perceived as 0:08:14.560 --> 0:08:18.040 a lower deeper note or tone, and a high frequency, 0:08:18.040 --> 0:08:21.760 with those peaks and troughs moving gradually more closer together, 0:08:21.840 --> 0:08:23.160 is going to be perceived. 0:08:22.920 --> 0:08:24.560 As a higher pitch. 0:08:24.800 --> 0:08:24.920 Right. 0:08:25.280 --> 0:08:26.760 A good way to think about this too, is if 0:08:26.760 --> 0:08:29.600 anyone's familiar with the instrument the theremon. There are two 0:08:29.640 --> 0:08:32.680 controls on a theremin. One is the antenna that goes upward, 0:08:32.679 --> 0:08:35.000 and there's an antenna on the side. The antentna on 0:08:35.040 --> 0:08:37.600 the side, you use your hand by moving it closer 0:08:37.960 --> 0:08:40.960 to or farther away, you are changing the amplitude, and 0:08:41.000 --> 0:08:44.199 that's perceived as a change in volume. The antenna going up. 0:08:44.200 --> 0:08:46.679 As you move your hand closer to it or farther away, 0:08:46.720 --> 0:08:49.800 you are changing the frequency. So with those two controls 0:08:49.840 --> 0:08:52.800 you can basically shape the way the sound is. 0:08:52.760 --> 0:08:56.440 Perceived, right, And it's important to remember these things because, 0:08:57.559 --> 0:09:01.240 as it turns out, different approaches to sell proofing are 0:09:01.360 --> 0:09:03.559 effective for different frequencies. 0:09:03.640 --> 0:09:05.640 Definitely, right, So there might be one. 0:09:05.360 --> 0:09:07.880 That you're like, oh, this is this is perfect. I 0:09:08.120 --> 0:09:11.000 can't hear my neighbors anymore. But then it turns out 0:09:11.040 --> 0:09:14.040 that when your neighbors put on an album that has 0:09:14.040 --> 0:09:16.280 a lot of base in it, it comes right through. 0:09:16.360 --> 0:09:18.000 Or start yelling at each other for whatever. 0:09:18.440 --> 0:09:20.360 Yeah, if the amplitude is loud enough, it may be 0:09:20.440 --> 0:09:23.600 that your soundproofing isn't going to be us. 0:09:23.640 --> 0:09:25.520 When people yell, sometimes they tend to raise. 0:09:25.360 --> 0:09:27.320 The pitch all right, right right, the pitch goes up 0:09:27.400 --> 0:09:29.880 enough that I got you. Yeah, So these are things 0:09:29.920 --> 0:09:31.920 that you have to take into consideration if you're trying 0:09:31.920 --> 0:09:35.439 to soundproof, and obviously what you are trying to accomplish, 0:09:35.520 --> 0:09:38.640 like the reason why you're soundproofing, that'll play into it 0:09:38.640 --> 0:09:40.320 as well, because if all you're trying to do is 0:09:40.400 --> 0:09:42.839 just make it quieter so that you know, you don't 0:09:42.880 --> 0:09:45.640 have like you're designing a building, maybe it's a hotel, 0:09:45.960 --> 0:09:49.080 and you want to make sure that the people talking 0:09:49.080 --> 0:09:52.120 in one room doesn't bleed over into other rooms. That's 0:09:52.280 --> 0:09:54.800 one type of soundproofing. If you're trying to make a 0:09:54.880 --> 0:09:57.680 professional recording studio, that's another type. 0:09:57.800 --> 0:09:58.040 Well. 0:09:58.040 --> 0:10:01.920 From a construction standpoint, like the base level soundproofing is drywall, 0:10:02.120 --> 0:10:04.840 so you have drywall, and that is where if you're 0:10:04.880 --> 0:10:07.040 in a hotel that only uses drywall, people are gonna 0:10:07.040 --> 0:10:08.960 be able to hear every single thing that's going on 0:10:09.000 --> 0:10:09.400 next door. 0:10:09.559 --> 0:10:09.640 Right. 0:10:09.720 --> 0:10:12.680 It's when you start basically stuffing that drywall with other 0:10:12.840 --> 0:10:16.920 denser materials or you know, highly rated soundproofing materials, that's 0:10:16.960 --> 0:10:19.720 when you can really cut down on that transfer between 0:10:19.720 --> 0:10:20.200 the rooms. 0:10:20.400 --> 0:10:20.640 Right. 0:10:20.679 --> 0:10:24.920 And also there are some other techniques you could use 0:10:24.920 --> 0:10:27.720 as well that I'll get into that, and it's all 0:10:27.760 --> 0:10:30.120 about how do you make it harder for the sound 0:10:30.200 --> 0:10:32.439 to travel from one place to another, because sound is 0:10:32.440 --> 0:10:34.679 going to travel no matter what. It's not like we 0:10:34.760 --> 0:10:40.080 have created a material that just sucks up sound totally. 0:10:40.600 --> 0:10:43.320 We've got a lot of materials that resist vibration and 0:10:43.360 --> 0:10:46.200 that means that they don't transfer sound very well. But 0:10:47.080 --> 0:10:49.559 and in fact the studio has some of that around us. 0:10:49.920 --> 0:10:52.120 But you know, there's other stuff you have to take 0:10:52.120 --> 0:10:56.640 into consideration as well. Now, there are four general elements 0:10:56.679 --> 0:10:59.320 to soundproofing, and we've we've kind of touched on a 0:10:59.400 --> 0:11:02.360 few of them, but one of the big ones is 0:11:02.720 --> 0:11:07.600 called decoupling. Now, decoupling is a construction term. When you're 0:11:07.600 --> 0:11:11.680 talking about decoupling, you're talking about the way the walls 0:11:11.760 --> 0:11:15.079 of the soundproofed area are actually constructed. So you were 0:11:15.120 --> 0:11:18.160 just talking about dry wall. The typical way a wall 0:11:18.240 --> 0:11:22.040 is constructed is you've got studs and attached to the 0:11:22.080 --> 0:11:25.280 studs are the anchor points for the dry wall. And 0:11:26.120 --> 0:11:30.360 in a typical wall, the studs are connected on either 0:11:30.440 --> 0:11:32.959 side by drywall for one side of the wall and 0:11:33.000 --> 0:11:34.400 dry wall for the other side of the wall. So 0:11:35.880 --> 0:11:37.760 if you can think of it like the interior wall 0:11:37.840 --> 0:11:41.120 versus the exterior wall of a room, The problem with 0:11:41.200 --> 0:11:44.480 that is that when sound hits the dry wall, then 0:11:44.600 --> 0:11:47.520 sound can travel through the dry wall through the studs, 0:11:47.720 --> 0:11:50.720 which transmits sound. They're a pretty good conductor for sound 0:11:51.120 --> 0:11:53.080 to the other side of the drywall, and then you 0:11:53.160 --> 0:11:55.959 get sound bleeding out or you have sound bleeding in 0:11:56.040 --> 0:12:00.440 from the outside. So decoupling is a process where you 0:12:00.440 --> 0:12:05.120 would build a wall so that the studs don't touch 0:12:05.240 --> 0:12:05.960 both sides of. 0:12:05.960 --> 0:12:07.120 The wall exactly. 0:12:07.200 --> 0:12:09.560 You would have a series of studs that one side 0:12:09.600 --> 0:12:12.640 the interior wall are attached to, and a different series 0:12:12.679 --> 0:12:15.480 of studs that the exterior wall are attached to. They 0:12:15.520 --> 0:12:20.160 both extend well into the gap between the two walls, 0:12:20.200 --> 0:12:22.120 but they don't touch the other side. 0:12:22.200 --> 0:12:26.480 So one side could be receiving sound waves and potentially 0:12:26.480 --> 0:12:29.360 transfer those but since they're not touching, it's much more 0:12:29.360 --> 0:12:30.640 difficult for that to happen. 0:12:30.440 --> 0:12:32.680 Right, because air is not as good a conductor of 0:12:32.760 --> 0:12:35.360 sound as a solid object is, which is weird. 0:12:35.400 --> 0:12:37.280 You wouldn't think that because I mean, here we are 0:12:37.280 --> 0:12:39.400 in a room talking to each other, right, and the 0:12:39.440 --> 0:12:41.719 air is basically what's connecting us. 0:12:41.960 --> 0:12:44.040 But the interesting thing though, is that the way you 0:12:44.040 --> 0:12:46.240 can tell this, it's very easy way to tell it's 0:12:46.280 --> 0:12:49.160 the old kid game of a telephone where you get 0:12:49.200 --> 0:12:52.920 two cans in a string, right, you punch holes in 0:12:52.920 --> 0:12:54.960 the bottom of the cans, you run the string through 0:12:55.000 --> 0:12:57.840 the holes, you stretch it taut, and then you can 0:12:57.880 --> 0:13:00.520 whisper into one can and hear it on the other side. 0:13:00.600 --> 0:13:03.440 But if you whisper that same volume across the room, 0:13:03.480 --> 0:13:06.880 you can't hear it. So again, that shows that the 0:13:07.559 --> 0:13:11.120 physical media is actually more or medium i should say, 0:13:11.200 --> 0:13:14.720 is actually more efficient at transferring the sound than air is. 0:13:15.160 --> 0:13:20.200 So air pockets are actually really important when you're soundproofing, 0:13:20.360 --> 0:13:24.520 you know, designing a soundproof room. Typically you would pair 0:13:24.640 --> 0:13:28.000 decoupling with some of the other elements, and I'll go 0:13:28.040 --> 0:13:29.640 ahead and mention what those elements are, and then we'll 0:13:29.679 --> 0:13:32.040 talk more about how you would put it all together. 0:13:32.640 --> 0:13:37.600 So you've got absorption another important element. This is obviously 0:13:38.120 --> 0:13:42.880 using a material that slows down sound. It absorbs some 0:13:42.920 --> 0:13:45.679 of the sounds, so that sound essentially loses some of 0:13:45.720 --> 0:13:49.560 its energy and it thus is quieter. It doesn't it 0:13:49.600 --> 0:13:52.520 doesn't leak out as much because the amplitude gets reduced 0:13:52.520 --> 0:13:57.200 as a result. So absorption you achieve usually through using 0:13:57.240 --> 0:14:01.360 some sort of insulation material like I mean, fiberglass is 0:14:01.400 --> 0:14:04.240 a simple example where you would put that in the wall, 0:14:04.440 --> 0:14:07.400 in the gap between the two sides of the wall 0:14:07.400 --> 0:14:08.520 to two pieces of drywall. 0:14:08.600 --> 0:14:10.040 I saw one even saying denim. 0:14:10.160 --> 0:14:12.800 You can use different like fabric type materials, the cotton 0:14:12.920 --> 0:14:13.480 or something like that. 0:14:13.480 --> 0:14:15.960 The important thing is that whatever you use, you cannot 0:14:16.040 --> 0:14:19.840 pack too densely exactly, because if it's too dense, that's 0:14:19.840 --> 0:14:21.880 going to transfer sound and you're back to the same 0:14:21.920 --> 0:14:23.920 problem you were at before. And you also want to 0:14:24.800 --> 0:14:27.000 still have some air gap there too. You don't want 0:14:27.400 --> 0:14:31.800 the material to make contact completely through the gap. You 0:14:31.840 --> 0:14:34.320 would pack kind of like half of the gap, a 0:14:34.320 --> 0:14:37.440 little more than half of the gap. Typically with insulating 0:14:37.440 --> 0:14:40.640 material you leave an air gap, and that really creates 0:14:40.760 --> 0:14:45.760 a great cushion for sound. We'll talk a little bit 0:14:45.760 --> 0:14:48.640 more about how that can go wrong, though. The coupling 0:14:48.720 --> 0:14:52.120 in particular can make certain things a little more difficult. 0:14:52.160 --> 0:14:56.680 There's also damping sound dampening. This is where you use 0:14:56.720 --> 0:15:00.280 some sort of material that resists vibration. So like the 0:15:00.320 --> 0:15:02.720 foam we have here, there's some we've got some dampening 0:15:02.760 --> 0:15:04.680 foam in here, but the typically you look at a 0:15:04.720 --> 0:15:08.520 lot of things like adhesives that are used to dampen sound. 0:15:09.320 --> 0:15:11.280 One of the ones I keep hearing about over and 0:15:11.320 --> 0:15:16.240 over is green glue. Green glue is yeah, so it's 0:15:16.360 --> 0:15:20.680 very popular, particularly apparently in Canada, but it's popular along 0:15:20.800 --> 0:15:24.440 among soundproofing technicians. It is considered to be one of 0:15:24.440 --> 0:15:28.760 the most effective for the least amount of money solutions 0:15:28.800 --> 0:15:32.240 for sound damping material. But typically this would be a 0:15:32.320 --> 0:15:35.520 layer that would also be part of your wall that 0:15:35.720 --> 0:15:39.920 resists the vibration of sound and so it won't transfer 0:15:40.000 --> 0:15:45.480 sound as well. It's again something that you would apply 0:15:45.640 --> 0:15:48.760 between two constrained layers, so it's not like it's not 0:15:48.800 --> 0:15:51.720 like you would coat this on the interior wall. That 0:15:51.720 --> 0:15:53.440 would be a bad idea. It would be on the 0:15:54.960 --> 0:15:57.000 backside of the interior wall. 0:15:57.080 --> 0:15:59.080 It might even be something you could use as an 0:15:59.120 --> 0:16:03.320 adhesive for other sound dampening material exact acoustic Follmer tile. 0:16:03.760 --> 0:16:08.760 And then the last element is really the simplest is mass. 0:16:09.000 --> 0:16:11.680 It's just that heavier things are harder to move than 0:16:11.800 --> 0:16:15.360 lighter things, right, It's just the basic idea, like if 0:16:15.400 --> 0:16:19.720 you had a cart filled with concrete blocks, it would 0:16:19.760 --> 0:16:21.520 be a little heavy to push. But if you had 0:16:21.520 --> 0:16:23.440 that same cart and it was filled with feathers. It's 0:16:23.480 --> 0:16:23.960 easy to. 0:16:23.880 --> 0:16:25.240 Push, So I've got something for you. 0:16:25.560 --> 0:16:27.840 Yeah, it uses all of those elements in a pretty 0:16:27.960 --> 0:16:31.600 perfect example, one of the more perfect examples of soundproofing 0:16:31.600 --> 0:16:34.080 that we can see in the real world. I'm not 0:16:34.080 --> 0:16:37.000 sure I think Microsoft has maybe outdone them at this point, 0:16:37.160 --> 0:16:40.080 but there is a place in Minneapolis, Minnesota called ore 0:16:40.160 --> 0:16:44.080 Field Laboratories and it contains what was I believe again 0:16:44.120 --> 0:16:47.600 until recently, the world's most silent room. 0:16:48.160 --> 0:16:50.280 Yes, world record for the most silent room. 0:16:50.440 --> 0:16:54.360 It is ninety nine point nine to nine percent sound absorbent, 0:16:54.880 --> 0:16:57.720 and in order to accomplish this, it uses a combination 0:16:58.000 --> 0:17:02.600 of very very very heavy materials. It's got concrete walls, 0:17:03.120 --> 0:17:06.480 steel reinforcement, and then on the inside of the room, 0:17:06.640 --> 0:17:09.000 I'm looking at a picture right now, it has these 0:17:09.119 --> 0:17:13.040 alternating sort of thin looking things. So you've got like 0:17:13.160 --> 0:17:16.600 three and then going from left to right, and then 0:17:16.640 --> 0:17:19.560 three right next to it, going vertically, and they alternate 0:17:19.600 --> 0:17:23.719 throughout every panel in this room and then even on 0:17:23.760 --> 0:17:26.399 the floor. And what you stand on is a metal 0:17:26.520 --> 0:17:29.440 grate that goes on top of another series of these 0:17:29.480 --> 0:17:32.320 alternating little units, and. 0:17:32.359 --> 0:17:36.440 Apparently The longest anyone has been able. 0:17:36.240 --> 0:17:38.720 To stand being in this room alone with the lights 0:17:38.760 --> 0:17:41.359 out is forty five minutes, because people start to hallucinate 0:17:41.720 --> 0:17:43.720 right this level of silence. 0:17:43.840 --> 0:17:46.159 I've heard such things. It's the sort of thing every 0:17:46.200 --> 0:17:48.520 time I hear it, I have the reaction that I 0:17:48.520 --> 0:17:51.080 think ninety nine percent of people have, which is I 0:17:51.160 --> 0:17:53.680 bet I could go longer. Sure, And of course I'd 0:17:53.720 --> 0:17:55.800 probably be in there for like three minutes and be 0:17:55.880 --> 0:17:58.880 convinced I'd been in there for three hours, because once 0:17:58.920 --> 0:18:02.119 you get to a point where or something that you 0:18:02.280 --> 0:18:05.720 have taken for granted, you know, just the ambient sounds 0:18:05.720 --> 0:18:09.280 that you can hear once that's gone, that really does 0:18:09.400 --> 0:18:14.919 make a big difference, and it is a psychologically powerful experience. 0:18:14.960 --> 0:18:16.560 But I still kind of want. 0:18:16.320 --> 0:18:16.800 To do it. 0:18:17.320 --> 0:18:20.560 Yeah, that's a great way of kind of summing up 0:18:20.640 --> 0:18:23.080 all of these elements. Now, if you want to really 0:18:23.119 --> 0:18:25.600 sound proof of room, the best thing to do is 0:18:25.640 --> 0:18:28.359 to incorporate as many of those as you possibly can, 0:18:28.480 --> 0:18:32.199 because they're different. Ones are good for different parts of 0:18:32.240 --> 0:18:35.560 that frequency range we're talking about, So some of them 0:18:35.600 --> 0:18:38.320 are really good for those mid to high range frequencies. 0:18:38.320 --> 0:18:40.520 Some of them are a little better at the low frequencies. 0:18:40.840 --> 0:18:43.440 So obviously you want to have a good combination otherwise 0:18:43.480 --> 0:18:47.040 you're gonna have certain sounds come through even if you've 0:18:47.240 --> 0:18:50.040 perfectly blocked the room for other ones, and that can 0:18:50.080 --> 0:18:51.040 be really frustrating. 0:18:51.080 --> 0:18:53.359 There's literally a cutoff or a threshold where if you 0:18:53.920 --> 0:18:57.840 looked on a graph that can show you what frequencies 0:18:57.840 --> 0:19:02.359 are happening, you could literally track okay, at this frequency, 0:19:02.680 --> 0:19:03.600 now I can hear it. 0:19:04.960 --> 0:19:06.880 Noel and I will be back to talk more about 0:19:06.920 --> 0:19:20.199 how soundproofing works after this quick break. So kind of 0:19:20.200 --> 0:19:24.679 going back to decoupling a little bit, the size of 0:19:24.720 --> 0:19:27.600 the air cavity between the two sides of the decoupled 0:19:27.640 --> 0:19:33.399 wall determines something called the resonant frequency of that So 0:19:34.520 --> 0:19:38.560 here's one of the problems with decoupling. That air cavity 0:19:38.680 --> 0:19:41.400 ends up acting kind of like a spring, right, So 0:19:41.440 --> 0:19:44.080 springs actually have a resonant frequency, and if you end 0:19:44.200 --> 0:19:47.720 up vibrating something at the resonant frequency, it causes that 0:19:47.760 --> 0:19:49.920 thing to vibrate very very easily. 0:19:50.080 --> 0:19:52.080 Sure, the big example of this. 0:19:52.080 --> 0:19:55.560 That everyone is familiar with is the crystal glass. Absolutely, 0:19:55.720 --> 0:19:58.880 the opera singer hitting that note, that's the resonant frequency 0:19:58.920 --> 0:20:00.720 for it you can actually see the last to form 0:20:00.760 --> 0:20:01.840 and ultimately break. 0:20:02.520 --> 0:20:05.560 Now or even someone that can play those glasses where 0:20:05.560 --> 0:20:07.440 they fill it up with water and run their finger 0:20:07.480 --> 0:20:08.240 around the rim. 0:20:08.720 --> 0:20:10.760 In order for it to start making that tone, it 0:20:10.800 --> 0:20:14.399 has to reach that resonant frequency exactly, So basically self 0:20:14.440 --> 0:20:15.640 oscillate exactly. 0:20:15.680 --> 0:20:19.080 So here's the problem with the decoupled walls is that 0:20:19.080 --> 0:20:22.520 that air gap, because it's acting like a spring and 0:20:22.560 --> 0:20:26.280 because it can resonate if it's not at the proper 0:20:26.560 --> 0:20:29.680 thickness for the air gap, that resonant frequency may be 0:20:29.920 --> 0:20:33.000 within the range of sounds that you're going to generate 0:20:33.040 --> 0:20:35.280 either inside or outside the room, within the range of 0:20:35.359 --> 0:20:38.640 human hearing, which means they're going to impact that sound 0:20:38.720 --> 0:20:42.639 proofing it. If something actually is played at that frequency, 0:20:42.880 --> 0:20:44.840 it'll go Not only will it go through the wall, 0:20:45.000 --> 0:20:47.440 it'll go through the wall more easily than it would 0:20:47.480 --> 0:20:51.879 have if you hadn't decoupled the wall because that resonance. 0:20:52.880 --> 0:20:55.000 So that is one of the things you actually have 0:20:55.040 --> 0:20:57.919 to take into account. And one of the solutions to 0:20:57.960 --> 0:21:01.800 that is don't make it too thin of an air gap. 0:21:03.440 --> 0:21:07.800 So another way of experimenting this with this yourself, if 0:21:07.800 --> 0:21:10.720 you want to just have some fun, And by fun, 0:21:10.760 --> 0:21:14.119 I mean like you know, mister Wizard style fun. You 0:21:14.160 --> 0:21:16.560 get a bottle and you know, if you blow across 0:21:16.640 --> 0:21:20.480 the opening of the bottle, it produces a tone. Well, 0:21:20.520 --> 0:21:23.080 it doesn't matter how hard you blow, it's always going 0:21:23.160 --> 0:21:26.119