WEBVTT - Home Theatre 102: Screens and Sounds 0:00:04.400 --> 0:00:07.800 Welcome to Tech Stuff, a production from I Heart Radio. 0:00:12.080 --> 0:00:14.960 Hey there, and welcome to tech Stuff. I'm your host, 0:00:15.120 --> 0:00:18.200 Jonathan Strickland. I'm an executive producer with I Heart Radio, 0:00:18.280 --> 0:00:22.760 and I love all things tech, and last week I 0:00:22.800 --> 0:00:26.800 started talking about home theater basics, and I really started 0:00:26.840 --> 0:00:31.160 with televisions and projectors, right, talking about the screen because 0:00:31.200 --> 0:00:34.000 that typically is one of those things that draws our 0:00:34.040 --> 0:00:36.440 attention first. Right, We talked a bit about L E 0:00:36.560 --> 0:00:41.320 D screens, O L E D screens, projector screens, the 0:00:41.360 --> 0:00:45.080 differences between h D t V four K and eight K, 0:00:45.800 --> 0:00:49.440 what h d R or high dynamic range is, and 0:00:49.760 --> 0:00:53.000 what refresh rates mean. But there are some other things 0:00:53.000 --> 0:00:54.760 that I want to chat about before we move on 0:00:54.800 --> 0:00:56.760 to sound. That's going to be the main focus of 0:00:56.800 --> 0:00:59.120 this episode. But we've got some stuff I got to 0:00:59.160 --> 0:01:02.920 clear up first because it does get confusing out there, 0:01:03.120 --> 0:01:08.039 and I didn't cover absolutely everything. So for example, as 0:01:08.080 --> 0:01:10.039 I mentioned in the previous episode, a lot of the 0:01:10.080 --> 0:01:14.399 specs with television's really comes down to marketing. Okay, so 0:01:16.080 --> 0:01:19.240 technology is is fun stuff, and there are a lot 0:01:19.280 --> 0:01:22.240 of hard things we can talk about, like as in 0:01:22.800 --> 0:01:27.559 defined things, Right, there are certain technologies where you've got 0:01:27.600 --> 0:01:30.520 a certain set of specifications, and anything that meets those 0:01:30.520 --> 0:01:35.120 specifications counts in. Anything that doesn't meet those specifications doesn't count. 0:01:35.600 --> 0:01:39.040 But with home theater, there's a lot of marketing jargon 0:01:39.160 --> 0:01:42.000 out there and a lot of different approaches to trying 0:01:42.040 --> 0:01:47.440 to create the best experience, and it gets really muddled. 0:01:47.720 --> 0:01:51.440 Companies find all sorts of different ways to quantify elements 0:01:51.480 --> 0:01:54.240 in a television and then they slap that number on 0:01:54.280 --> 0:01:57.800 a box. And these numbers can look really impressive, right 0:01:57.840 --> 0:02:01.840 if you just see the number, or like some interesting 0:02:02.000 --> 0:02:06.720 designation that's heavily trademarked, that might seem like, oh, this 0:02:06.800 --> 0:02:10.480 is really cool, it's really advanced, it's really good. Other 0:02:10.520 --> 0:02:13.840 companies will go a step further they incorporate some proprietary 0:02:13.840 --> 0:02:17.280 technology and their televisions. That makes it even more confusing, 0:02:17.360 --> 0:02:20.640 where this is something that you will only find in 0:02:20.760 --> 0:02:25.920 TVs from this particular company, and you ask, well, what 0:02:25.919 --> 0:02:30.200 does that mean, why is it there, what benefit does 0:02:30.200 --> 0:02:33.360 it give me? And is it compatible with everything I 0:02:33.400 --> 0:02:36.680 want to watch? So one of those companies that does this, 0:02:36.800 --> 0:02:38.960 and it's by no means the only one. I don't 0:02:38.960 --> 0:02:42.720 want to just single it out, but Samsung is one 0:02:42.760 --> 0:02:45.320 of those companies. So I talked about oh LEDs O 0:02:45.600 --> 0:02:48.320 L E D S. I did not, however, talk about 0:02:48.840 --> 0:02:52.960 q LEDs, a technology that Samsung promotes, and its television's 0:02:53.880 --> 0:02:58.919 q LEDs, according to Samsung, stands for quantum dot L 0:02:58.960 --> 0:03:03.200 E D t V. So that raises an obvious question, 0:03:03.440 --> 0:03:08.560 what the heck is a quantum dot. Technically, a quantum 0:03:08.600 --> 0:03:13.720 dot is a nanoscale crystal that when UV light hits 0:03:13.840 --> 0:03:18.320 that crystal, the crystal will emit various colors, and the 0:03:18.400 --> 0:03:22.880 color that the crystal emits depends upon the crystal's size. 0:03:23.440 --> 0:03:25.520 And that probably sounds a little bit weird. It kind 0:03:25.520 --> 0:03:28.160 of sounds like Star Wars E right, like a chaiber crystal. 0:03:28.560 --> 0:03:32.440 Your chiber crystal determines the color of your lightsaber blade. 0:03:32.960 --> 0:03:36.120 Almost the same sort of concept here, except we're talking 0:03:36.160 --> 0:03:39.280 about stuff on the nanoscale that, by the way, we're 0:03:39.320 --> 0:03:42.320 talking about like nanometer that means one billionth of a meter, 0:03:42.800 --> 0:03:47.200 so tiny that the quantum rules start to take effect. 0:03:47.880 --> 0:03:51.960 And all things quantum and nanoscale are a little weird 0:03:51.960 --> 0:03:55.200 because quantum mechanics do not necessarily work the same way 0:03:55.280 --> 0:03:59.000 classic physics do, at least not the way we understand 0:03:59.040 --> 0:04:01.600 it right. There's stuff it happens at the nano scale 0:04:02.200 --> 0:04:04.760 that just does not happen at the macro scale, and 0:04:04.800 --> 0:04:08.040 it seems almost magical to us because it's not the 0:04:08.080 --> 0:04:12.360 experience we have. Maybe if you can actually see the matrix, 0:04:12.560 --> 0:04:15.840 it all makes sense, like everything fits together. But right 0:04:15.880 --> 0:04:19.680 now we still have incredibly intelligent physicists who are trying 0:04:19.720 --> 0:04:23.320 to find ways of marrying the world of quantum mechanics 0:04:23.680 --> 0:04:28.280 with our understanding of classical physics. Anyway, let's say you've 0:04:28.279 --> 0:04:32.359 got a quantum dot that's six nanometers across, and you 0:04:32.480 --> 0:04:36.480 hit that quantum dot with light that's around four fifty 0:04:36.560 --> 0:04:39.440 nanometers in wavelength. That actually puts it in the neighborhood 0:04:39.520 --> 0:04:43.359 of blue light. Blue is in that that frequency range 0:04:43.920 --> 0:04:47.880 um that crystal or that wavelength range. I should say 0:04:47.920 --> 0:04:53.440 that crystal then will emit red light. That's six nanometer 0:04:53.800 --> 0:04:56.240 wide crystal. But if you were to build a quantum 0:04:56.279 --> 0:05:01.400 dot that's five nanometers wide and you that one with 0:05:01.520 --> 0:05:05.240 that same blue light, that crystal would emit orange light, 0:05:05.760 --> 0:05:09.200 and so on. So by just changing the size of 0:05:09.240 --> 0:05:12.440 the quantum dot, or making quantum dots of different sizes, 0:05:12.960 --> 0:05:17.880 you can create different light effects even using the same 0:05:18.000 --> 0:05:22.120 light source hitting all those different quantum dots. Quantum dots 0:05:22.440 --> 0:05:27.040 have lots of other potential applications besides television screens. Uh. 0:05:27.160 --> 0:05:30.360 The dots properties also depend on tons of different factors 0:05:30.400 --> 0:05:33.720 in addition to size, such as the shape of the 0:05:33.720 --> 0:05:36.320 crystal and whether or not the crystal is hollow or 0:05:36.360 --> 0:05:40.800 if it's solid, And there's some really cool biomedical applications, 0:05:40.839 --> 0:05:43.640 and beyond that, there's talk of quantum dots taking apart 0:05:43.680 --> 0:05:48.400 in self assembling nanocrystals as a nanotechnology that can build 0:05:48.440 --> 0:05:52.640 itself under the right conditions. But that's enough for us 0:05:52.680 --> 0:05:55.360 to cover for now, because we could do an entire 0:05:55.440 --> 0:05:59.839 episode about quantum dots and nanotechnologies and totally get off track. 0:06:00.320 --> 0:06:04.400 So a Samsung q LED t V is actually a 0:06:04.480 --> 0:06:07.760 variant on the l e ED l c D Television's 0:06:07.839 --> 0:06:11.360 l c D standing for liquid crystal display. So l 0:06:11.360 --> 0:06:14.320 e ED t vs use light emitting diodes that's what 0:06:14.480 --> 0:06:19.039 LED stands for, as tiny lamps that provide the light 0:06:19.320 --> 0:06:21.640 for a television screen. So all that light is coming 0:06:21.720 --> 0:06:26.080 from these little l e ED light sources. A liquid 0:06:26.120 --> 0:06:29.760 crystal display panel acts kind of like a shutter or 0:06:29.880 --> 0:06:33.000 shade for each of those lamps, and it allows a 0:06:33.040 --> 0:06:37.320 certain amount of light through to the screen in order 0:06:37.320 --> 0:06:41.120 to achieve the proper brightness or luminosity of a scene. 0:06:41.400 --> 0:06:45.160 And this also means that the little lamps are actually 0:06:45.200 --> 0:06:48.800 always on in the background, and some l e D 0:06:48.920 --> 0:06:53.800 screens aren't really able to show really dark colors effectively, 0:06:54.120 --> 0:06:56.919 meaning you kind of get lousy contrast ratio compared to 0:06:56.960 --> 0:07:01.480 oh LAD screens. Oh lads or organic light emitting diodes 0:07:01.839 --> 0:07:04.320 are different, and that each pixel in an old LAD 0:07:04.360 --> 0:07:07.440 screen emits its own light, and thus it can turn 0:07:07.440 --> 0:07:11.760 off entirely and achieve a true black on screen instead 0:07:11.760 --> 0:07:15.200 of this kind of dark gray, because there's actually a 0:07:15.320 --> 0:07:18.880 light shining through a liquid crystal, and some of that 0:07:18.960 --> 0:07:21.120 light is bleeding through the liquid crystal to get to 0:07:21.160 --> 0:07:24.360 the screen. So with oh leads you don't have a backlight. 0:07:24.440 --> 0:07:28.320 The old leads are both light and pixel and oh 0:07:28.440 --> 0:07:32.760 LAD screens are emissive, whereas l e D screens are transmissive, 0:07:33.400 --> 0:07:35.800 and a Q LEAD screen is also transmissive. It's a 0:07:35.840 --> 0:07:38.760 type of l E D, so Samsung's Q l e 0:07:38.880 --> 0:07:42.160 D screen includes a film of quantum dots in addition 0:07:42.200 --> 0:07:44.520 to the L E D and l c D elements, 0:07:45.120 --> 0:07:47.600 So the light passes through the film of the quantum 0:07:47.640 --> 0:07:50.400 dots in addition to everything else, I imagine that probably 0:07:50.400 --> 0:07:54.000 means that the lights behind the screen need to be 0:07:54.080 --> 0:07:57.040 even brighter in order to you know, push the right 0:07:57.040 --> 0:08:01.400 amount of light through all those it's including the extra 0:08:01.480 --> 0:08:04.280 layer of the quantum dot film. But the quantum dots 0:08:04.320 --> 0:08:09.200 are supposed to provide much more vibrant and realistic color representation, 0:08:09.280 --> 0:08:11.240 so the colors you get on screen are supposed to 0:08:11.320 --> 0:08:16.440 be more accurate and jump off the screen more effectively. Now, 0:08:16.600 --> 0:08:20.120 q laed screens typically can produce a much brighter picture 0:08:20.160 --> 0:08:23.040 than oh LAD screens do. So while oh lads are 0:08:23.040 --> 0:08:27.080 great for contrast and they work really well in dim rooms, 0:08:27.680 --> 0:08:30.160 q LED screens are more luminous and they can work 0:08:30.240 --> 0:08:33.400 better in brighter rooms. So even if you have like 0:08:33.440 --> 0:08:36.520 a lot of ambient light in your home theater space, 0:08:36.640 --> 0:08:38.800 or you're not even building a home theater you just want, 0:08:39.200 --> 0:08:41.400 you know, a good TV and you have to have 0:08:41.440 --> 0:08:43.640 a lot of windows or whatever, or a lot of 0:08:43.679 --> 0:08:47.360 other light in the space, these screens can be bright 0:08:47.520 --> 0:08:50.959 enough where they can overcome that that ambient light that's 0:08:51.000 --> 0:08:53.400 in your area. And they also work pretty well with 0:08:53.640 --> 0:08:56.760 HDR content, that high dynamic range where you're trying to 0:08:56.920 --> 0:09:00.120 reproduce colors in a really vibrant way. Now that is 0:09:00.160 --> 0:09:04.280 not to say that que lads are better than oh LEDs, 0:09:04.280 --> 0:09:06.760 but rather if you're in a bright setting, it can 0:09:06.840 --> 0:09:08.959 seem that way. This, by the way, is one of 0:09:09.000 --> 0:09:12.640 the reasons that's so dang hard to shop for television's 0:09:12.640 --> 0:09:16.480 because typically you go to a store that's lit with 0:09:16.520 --> 0:09:20.040 these bright, fluorescent, you know, lights, and it can mean 0:09:20.080 --> 0:09:23.680 that a television that technically will deliver a superior performance 0:09:23.760 --> 0:09:28.200 under normal viewing circumstances might not look the best simply 0:09:28.240 --> 0:09:30.880 because you're in a very bright environment, not in a 0:09:30.920 --> 0:09:33.920 home theater setting. That's why a lot of these places 0:09:33.960 --> 0:09:37.679 will have like a home theater room set up where 0:09:37.720 --> 0:09:40.320 at least a certain number of televisions can be shown 0:09:40.840 --> 0:09:45.320 without being in that bright environment. Then again, maybe if 0:09:45.320 --> 0:09:48.800 your home is brightly lit, then the experience you get 0:09:48.800 --> 0:09:50.760 in the store is exactly what you need, because you 0:09:50.800 --> 0:09:53.600 want to make sure that the screen you get is 0:09:53.640 --> 0:09:56.360 one that you know you can see everything on. Something 0:09:56.400 --> 0:09:58.800 else I didn't really cover in the last episode is 0:09:58.920 --> 0:10:03.840 viewing angle, but that is actually important to Again, this 0:10:03.960 --> 0:10:07.160 gets around the technology part. It's more about how you 0:10:07.200 --> 0:10:12.240 position the technology. Most shopping guides for television's assume that 0:10:12.280 --> 0:10:14.840 you will normally view the television pretty much dead on, 0:10:15.440 --> 0:10:18.280 sitting you know, directly across from it, so like at 0:10:18.280 --> 0:10:22.240 a zero degree angle straight line between you and the TV, 0:10:22.880 --> 0:10:25.320 and the center of the television would be positioned more 0:10:25.400 --> 0:10:29.240 or less at your eye level. Once you start moving 0:10:29.280 --> 0:10:32.560 that around, like changing the viewing angle, you start to 0:10:32.679 --> 0:10:36.760 encounter some issues, Like you would get the ideal experience 0:10:37.120 --> 0:10:40.760 under those circumstances, and once you deviate from those circumstances, 0:10:40.840 --> 0:10:44.400 you might encounter problems. For example, TVs that have l 0:10:44.480 --> 0:10:47.560 c D screens can have areas that appear brighter or 0:10:47.720 --> 0:10:51.320 darker from other viewing angles. So if you're sitting to 0:10:51.360 --> 0:10:56.200 the side or you wouldn't necessarily see the picture exactly 0:10:56.240 --> 0:10:58.320 as it should be. Or let's say your television is 0:10:58.360 --> 0:11:02.520 mounted closer to the ceiling, it might not be ideal 0:11:02.600 --> 0:11:06.080 either because your viewing angle is not the way that 0:11:06.160 --> 0:11:09.480 you know was thought of as being ideal. Oh, LED 0:11:09.559 --> 0:11:13.120 screens typically have a much more consistent viewing experience across 0:11:13.200 --> 0:11:16.320 multiple angles, So if you do want to mount a 0:11:16.400 --> 0:11:19.839 television close to your ceiling, then an old screen might 0:11:19.880 --> 0:11:23.199 be the way to go because it won't be as 0:11:23.240 --> 0:11:27.400 affected by that that extreme viewing angle as an l 0:11:27.480 --> 0:11:30.640 c D television would. One other thing I do need 0:11:30.679 --> 0:11:32.880 to mention about oh LED screens. This was actually brought 0:11:32.920 --> 0:11:36.440 up by someone on Twitter, and I apologize. I tried 0:11:36.480 --> 0:11:39.960 to find your tweet this morning, but I couldn't find it. 0:11:40.240 --> 0:11:42.280 I don't know what has happened. I don't know why 0:11:42.280 --> 0:11:45.880 it's disappeared from my mentions. But someone actually pointed out 0:11:45.920 --> 0:11:49.520 in our last episode that, like plasma displays, oh LED 0:11:49.600 --> 0:11:54.000 screens can experience burning. Burning happens when a screen holds 0:11:54.080 --> 0:11:57.400 a particular image for a really long time. And I'm 0:11:57.440 --> 0:12:01.800 talking like hours and hours of hour of holding that image. 0:12:02.040 --> 0:12:04.360 So imagine like you have a video game playing and 0:12:04.400 --> 0:12:08.320 you pause the game and the system never goes into 0:12:08.320 --> 0:12:11.240 sleep mode. It just holds that image there, and then 0:12:11.280 --> 0:12:13.440 you go on vacation for two months and you come back. 0:12:13.760 --> 0:12:16.760 That's what I'm talking about. So in these cases, that 0:12:16.880 --> 0:12:19.920 image of whatever was held on the screen for so 0:12:19.960 --> 0:12:24.200 long burns into the display. Uh. In this case, it 0:12:24.240 --> 0:12:27.080 means that the particular oh LED elements have held that 0:12:27.160 --> 0:12:29.840 image so long that they kind of hold onto a 0:12:30.040 --> 0:12:34.600 ghost of that image forever. So if you try watching anything, 0:12:35.080 --> 0:12:38.200 you'll end up seeing sort of a transparent image of 0:12:38.240 --> 0:12:41.320 whatever it was that was burned on the screen. Usually 0:12:41.360 --> 0:12:44.960 what you'll get is actually image retention, not image burning, 0:12:45.480 --> 0:12:48.040 which is more like the experience of having, you know, 0:12:48.080 --> 0:12:50.120 a bright light flash in your eyes for a second, 0:12:50.200 --> 0:12:52.960 and you get that after image, that retinal after image. 0:12:53.320 --> 0:12:56.000 That can happen with oh led screens, but that's temporary. 0:12:56.080 --> 0:12:58.600 The retained image will fade and before long you wouldn't 0:12:58.600 --> 0:13:01.760 even remember that was on there. But it is possible 0:13:02.040 --> 0:13:05.880 for those kind of ghostly images to become a permanent fixture. 0:13:06.200 --> 0:13:08.920 If it's held long enough, it goes beyond being an 0:13:08.920 --> 0:13:12.120 afterimage and it becomes burning. One way this can happen 0:13:12.559 --> 0:13:14.320 is if you have a television that's set to a 0:13:14.320 --> 0:13:17.240 specific channel, and let's say that channel has a logo 0:13:17.440 --> 0:13:20.880 up on screen pretty much all the time. So you've 0:13:20.880 --> 0:13:23.679 got a television running, say a twenty four hour news 0:13:23.720 --> 0:13:27.439 station like CNN or Fox News or something. The logo 0:13:27.800 --> 0:13:31.200 in the corner can actually eventually burn into the screen. 0:13:31.280 --> 0:13:33.040 If you're just showing that all the time and the 0:13:33.040 --> 0:13:36.240 TV never goes off. Now, for most people, this isn't 0:13:36.240 --> 0:13:39.040 a problem because most people typically watch a variety of 0:13:39.120 --> 0:13:43.280 things and that prevents burning from happening. Uh if it's 0:13:43.280 --> 0:13:45.800 like a TV that's in say an office setting, and 0:13:45.880 --> 0:13:49.640 it always has CNN on, well, then you're more likely 0:13:49.679 --> 0:13:52.480 to see burning with a no LED screen under those cases. 0:13:52.800 --> 0:13:55.240 I like to think of this as, uh, those oh 0:13:55.360 --> 0:13:58.160 LAD components that hold onto the image are really just 0:13:58.200 --> 0:14:01.120 saying this is all I know how to do now, 0:14:01.240 --> 0:14:05.400 which frankly is a mood that I identify with. And 0:14:05.480 --> 0:14:08.800 technically l c D based televisions can also have burn 0:14:08.840 --> 0:14:12.920 into but it is far less common it. It requires, 0:14:13.000 --> 0:14:15.439 like like I said, ages and ages and ages of 0:14:15.480 --> 0:14:17.920 holding the same sort of image for it to happen 0:14:17.920 --> 0:14:21.800 with your typical l c D based televisions. But even 0:14:21.840 --> 0:14:24.600 with oh LAD, it's something that the average person is 0:14:24.680 --> 0:14:28.760 not likely to encounter. So while it is possible, I 0:14:28.800 --> 0:14:31.560 don't want to discourage people from, say, going to look 0:14:31.600 --> 0:14:35.080 at oh LED screens because it's not likely to happen 0:14:35.080 --> 0:14:39.600 to you. All Right, That, I think means we're finally 0:14:40.000 --> 0:14:44.880 ready to transition away from visuals and talk more about sound. 0:14:45.480 --> 0:14:48.440 So we're gonna take a quick break and when we 0:14:48.480 --> 0:14:51.200 come back, we're gonna pick up with the sound component 0:14:51.240 --> 0:14:53.840 of home theater systems, which for a lot of home 0:14:53.920 --> 0:14:58.080 theater enthusiasts, they argue that as the most important component. 0:14:58.320 --> 0:15:01.480 That you know, your screen is important, obviously, but that 0:15:01.600 --> 0:15:04.880 your sound is even more important than that. So if 0:15:04.880 --> 0:15:08.000 you were to like budget out of home theater, you 0:15:08.040 --> 0:15:11.440 would want to put more money towards your sound system 0:15:11.480 --> 0:15:16.040 than your television or your screen and projector. I don't 0:15:16.040 --> 0:15:18.680 know that I agree with that. I probably do because 0:15:18.720 --> 0:15:20.840 I do really like sound. I mean, I'm in podcasting 0:15:20.880 --> 0:15:24.320 after all. But um yeah, we're gonna get into that 0:15:24.680 --> 0:15:36.240 after this quick break. So we'll be right back now 0:15:36.280 --> 0:15:38.640 to talk about sound. We're gonna need to have a 0:15:38.680 --> 0:15:41.960 quick refresher on what sound actually is because it is 0:15:42.040 --> 0:15:45.400 important and longtime listeners of tech stuff y'all know all 0:15:45.440 --> 0:15:47.920 this by heart by now, but we get new folks 0:15:48.000 --> 0:15:50.840 all the time. So let's talk about the physics of sound, 0:15:51.240 --> 0:15:54.120 all right. So sound, when you really break it down, 0:15:54.840 --> 0:15:59.240 is essentially vibration. It's atoms and molecules that are vibrating 0:15:59.280 --> 0:16:02.200 against each other in a way that extends outward from 0:16:02.440 --> 0:16:05.880 the point of origin, and it extends outward in all 0:16:05.880 --> 0:16:08.680 directions from the point of origin. So as long as 0:16:08.720 --> 0:16:12.960 there are enough molecules of whatever, this vibration is moving 0:16:12.960 --> 0:16:17.000 through the medium. In other words, sound can travel. That's 0:16:17.000 --> 0:16:19.680 why sound doesn't travel in space, because there's a lack 0:16:20.120 --> 0:16:23.400 of molecules that are close enough to vibrate against each other, 0:16:23.720 --> 0:16:26.520 so sound can't travel out there. We talk about the 0:16:26.560 --> 0:16:29.680 speed of sound a lot, particularly with stuff like air 0:16:29.720 --> 0:16:34.000 travel or you know, projectiles, but that phrase is deceptive 0:16:34.040 --> 0:16:37.680 because sounds speed is dependent upon the medium through which 0:16:37.680 --> 0:16:40.400 it travels, so sound does not travel at the same 0:16:40.440 --> 0:16:44.400 speed through everything. Sound will travel at a different speed 0:16:44.440 --> 0:16:47.880 through solids versus liquids, versus gases, and it gets even 0:16:47.880 --> 0:16:51.280 more complicated from there. Most of the time we can 0:16:51.320 --> 0:16:53.560 just say speed of sound to mean how fast sound 0:16:53.600 --> 0:16:57.520 travels through the air, because that's how we typically experience sound. 0:16:57.920 --> 0:17:00.960 But even this needs some qualifiers because sound will travel 0:17:01.000 --> 0:17:04.359 at different speeds through cold air then it will through 0:17:04.400 --> 0:17:07.840 hot air, and different speeds through dry air than it 0:17:07.880 --> 0:17:10.760 will through humid air, so we actually do have to 0:17:10.760 --> 0:17:14.040 get very specific. That usually means we say sound travels 0:17:14.040 --> 0:17:19.200 at three per second through dry air at twenty degrees celsius, 0:17:19.200 --> 0:17:23.840 which is sixty degrees fahrenheit. So why does that temperature matter. Well, 0:17:23.880 --> 0:17:26.520 if you remember your physics, when you heat gases up, 0:17:26.640 --> 0:17:29.480 they expand and the molecules get more energy and they 0:17:29.520 --> 0:17:33.600 move around a lot more. Colder gases are more dense, 0:17:33.640 --> 0:17:36.879 the molecules move less. In fact, if you can cool 0:17:36.960 --> 0:17:41.720 down the gas to absolute zero, the lowest temperature you 0:17:41.720 --> 0:17:46.320 can get, you stop molecular movement entirely. But typically we 0:17:46.400 --> 0:17:50.119 are not talking about temperatures that cold. Sound will travel 0:17:50.280 --> 0:17:52.879 faster through warm air than cold air, and you can 0:17:52.920 --> 0:17:55.080 think of the molecules as being a little bit more 0:17:55.119 --> 0:17:58.159 loosey goosey, and so they'll move around more easily, and 0:17:58.200 --> 0:18:02.000 thus vibration will pass through this more easily. There's less 0:18:02.040 --> 0:18:06.080 resistance anyway. Now that's super important for our home theater discussion. 0:18:06.440 --> 0:18:08.600 It's just good to have a basic handle on the 0:18:08.600 --> 0:18:12.440 physics of sound before you start talking about sound setups. Now, 0:18:12.520 --> 0:18:16.600 some things that are super important about how sound behaves 0:18:17.080 --> 0:18:21.080 is that when it moves through one medium and encounters another, 0:18:21.240 --> 0:18:24.520 things change. So, for example, let's say you're swimming underwater 0:18:25.080 --> 0:18:28.919 and someone above water is shouting your name. If you 0:18:29.080 --> 0:18:32.040 hear that at all, it's going to be pretty muffled, 0:18:32.200 --> 0:18:34.560 which is weird because you know, sound travels pretty well 0:18:34.560 --> 0:18:37.000 through liquids. I mean, whales are able to sing to 0:18:37.080 --> 0:18:43.119 each other miles apart. Right, Sound can travel enormous distances underwater. 0:18:43.720 --> 0:18:47.840 But when sound encounters a boundary between two mediums or 0:18:48.080 --> 0:18:52.520 or media, if you prefer like moving from the air 0:18:52.760 --> 0:18:56.679 to the water, then typically one of three things happens. 0:18:57.119 --> 0:19:00.440 Sound waves get absorbed, which means, you know it, they 0:19:00.480 --> 0:19:03.639 just kind of get absorbed by physical material and they 0:19:03.680 --> 0:19:07.760 no longer bounce around. Or sound waves get refracted, or 0:19:07.800 --> 0:19:11.040 sound waves get reflected, and this is super important for 0:19:11.080 --> 0:19:14.639 home theater setups. So let's just get refraction out of 0:19:14.640 --> 0:19:16.440 the way, because most of you don't need to worry 0:19:16.480 --> 0:19:18.520 about it unless you plan to set up your home 0:19:18.560 --> 0:19:22.720 theater system inside a glass cube and then watch everything 0:19:22.720 --> 0:19:25.640 from outside the cube, which you know, don't do that. 0:19:26.200 --> 0:19:28.720 Between the refraction of sound and the glare that you're 0:19:28.720 --> 0:19:31.199 gonna get on the glass, it would be a subpar experience. 0:19:31.640 --> 0:19:35.000 But with a refraction, waves traveling through one medium will 0:19:35.119 --> 0:19:38.880 change direction and speed as well as wavelength as they 0:19:38.880 --> 0:19:43.359 pass through the boundary of the one medium into another, 0:19:43.440 --> 0:19:46.240 such as from a gas to a liquid, or vice 0:19:46.359 --> 0:19:49.320 versa um. If you've ever noticed that a straw and 0:19:49.359 --> 0:19:51.600 a glass of water looks as though it's in one 0:19:51.600 --> 0:19:54.719 position above the water line and a different position below it, 0:19:54.800 --> 0:19:58.640 like it's offset, that's because light waves are refracting as 0:19:58.680 --> 0:20:01.880 they pass from the air to water. So light behaves 0:20:01.880 --> 0:20:05.000 in a very similar way. Sound does the same. Anyway, 0:20:05.040 --> 0:20:07.880 we're gonna leave that behind because refraction is not as 0:20:07.960 --> 0:20:13.280 important to us as reflection and absorption. If the density 0:20:13.320 --> 0:20:15.800 of the two mediums is extreme, Like if there's a 0:20:15.800 --> 0:20:18.080 difference in density where you're going from like gas to 0:20:18.280 --> 0:20:22.240 a hard solid, you're more likely to see reflection than 0:20:22.280 --> 0:20:26.159 you are refraction. With a reflection, a wave of traveling 0:20:26.200 --> 0:20:30.320 through one medium encounters a dense obstacle and then bounces 0:20:30.320 --> 0:20:33.159 off that obstacle. It cannot absorb into it, it cannot 0:20:33.240 --> 0:20:36.560 refract through it, so it bounces off it reflects. So 0:20:36.600 --> 0:20:39.520 in a home theater, sound traveling from speakers might encounter 0:20:39.680 --> 0:20:43.520 like a hardwood floor and thus bounce off the floor, 0:20:44.080 --> 0:20:46.280 and the angle of bounce is interesting. The law of 0:20:46.359 --> 0:20:50.480 reflection tells us that waves will bounce off an obstacle 0:20:50.600 --> 0:20:54.359 at an angle equal to the angle of approach. So, 0:20:54.400 --> 0:20:56.960 in other words, if sound is coming in at a 0:20:57.000 --> 0:21:00.760 thirty five degree angle, when it's hitting the ground, it 0:21:00.800 --> 0:21:03.920 will bounce off at a thirty five degree angle from 0:21:03.960 --> 0:21:06.280 the ground. If it's forty five degrees coming in, it 0:21:06.280 --> 0:21:08.840 will be forty five degrees coming out. If it's ninety degrees, 0:21:08.840 --> 0:21:12.080 it will be ninety degrees. Knowing this is really important 0:21:12.240 --> 0:21:15.640 because this comes into effect when we start talking about 0:21:15.680 --> 0:21:18.200 things like soundbars, which we may or may not get 0:21:18.240 --> 0:21:20.600 to in this episode. I'll find out when I get there, 0:21:21.040 --> 0:21:23.840 all right. Because of this fun fact of the law 0:21:23.960 --> 0:21:28.840 of reflection, people can create really cool effects in spaces, 0:21:28.920 --> 0:21:32.280 physical spaces. Folks figured this out a long, long long 0:21:32.320 --> 0:21:35.720 time ago, which is part of the reason why certain buildings, 0:21:35.760 --> 0:21:39.920 like certain churches and cathedrals in Europe, for example, are 0:21:39.960 --> 0:21:43.080 built in really similar styles. And part of the desired 0:21:43.080 --> 0:21:47.200 outcome was to create a structure that would reflect sound well. 0:21:47.800 --> 0:21:50.600 Because remember these things were built in the days before 0:21:50.680 --> 0:21:54.399 amplified sounds, so you didn't have microphones and speakers and stuff, 0:21:54.880 --> 0:21:58.359 and you had musical composers who would create sacred music 0:21:58.520 --> 0:22:03.439 knowing about the reflective effects, and they would create some 0:22:03.520 --> 0:22:07.760 truly remarkable pieces of music that to this day sound 0:22:07.880 --> 0:22:10.960 incredible if you happen to be inside one of those 0:22:10.960 --> 0:22:14.080 structures when a group performs it, because it was made 0:22:14.160 --> 0:22:18.440 for those spaces and those reflections end up creating effects 0:22:18.480 --> 0:22:21.119 that enhance the music. If you were to hear it 0:22:21.160 --> 0:22:23.720 outside of that building, it would sound like a totally 0:22:23.720 --> 0:22:26.560 different piece and you would lose some of that complexity. 0:22:26.600 --> 0:22:28.640 But the reason I bring it up here is that 0:22:28.680 --> 0:22:30.800 if you do have a lot of hard surfaces in 0:22:30.840 --> 0:22:36.320 your home theater room, like hardwood floors, woodwalls, maybe like 0:22:36.560 --> 0:22:40.359 a flat hard ceiling, then you're gonna get a lot 0:22:40.440 --> 0:22:44.400 of sound reflection, and that's not necessarily a good thing. 0:22:45.160 --> 0:22:49.160 If you want to create an immersive audio experience, then 0:22:49.240 --> 0:22:51.840 you want to be able to control how sound is 0:22:51.880 --> 0:22:55.040 going to reach the audience. So let's say it's you, 0:22:55.200 --> 0:22:58.560 like you're planning on being the person who primarily uses 0:22:58.640 --> 0:23:01.040 this home theater. You want to be able to control 0:23:01.119 --> 0:23:04.080 how sound gets to you, so that Let's say you're 0:23:04.080 --> 0:23:06.800 watching a really creepy horror movie and you want the 0:23:06.800 --> 0:23:10.880 sounds to be really specific and directional, so that when 0:23:10.920 --> 0:23:14.159 something happens, say off to the left to your left 0:23:14.480 --> 0:23:18.240 on screen, then you hear it on your left side. 0:23:18.320 --> 0:23:20.440 Maybe even more positional than that, maybe it sounds like 0:23:20.480 --> 0:23:23.639 it's coming up from behind your left shoulder. Well, you 0:23:23.680 --> 0:23:26.399 have to create a setup where all this can happen. 0:23:26.440 --> 0:23:29.320 And for that reason, a lot of home theater enthusiasts 0:23:29.359 --> 0:23:32.439 prefer to have carpeted floors, and they prefer to have 0:23:32.520 --> 0:23:35.560 walls that either have some form of baffling on them, 0:23:35.720 --> 0:23:40.760 like foam or fabric panels that absorb sound rather than 0:23:40.840 --> 0:23:44.680 reflect it, or they will put their home theater in 0:23:45.040 --> 0:23:48.120