Pragmatic 8: A Nice Quiet Serene Environment

12 January, 2014

CURRENT

In this episode John and Ben talk about noise. Noise is a big problem. A lot of people tend to overlook it. A lot of people tend to shrug it off like its no big deal. But you only get one set of ears, and once they’re wrecked you’re out of luck.

Transcript available
[MUSIC] >> This is Pragmatic, a weekly discussion show contemplating the practical application of technology. Exploring the real-world trade-offs, we look at how great ideas are transformed into products and services that can change our lives. Nothing is as simple as it seems. I'm Ben Alexander and my co-host is John Gigi. How are you doing, John? I'm doing very well. How are you doing, Ben? Doing great. Awesome. No, it's still pitch black out. A couple more weeks and we'll start to have sun at this time. Rumor has it that most of the vortex has moved on, though. The polar vortex. Yeah, it sounds very spooky. It's a bit creepy even. But it is a real thing. There was a lot of static that, oh, this is just the news media making stuff up. But it's a thing. It was really cold. Yeah, well, I saw the photo that you posted. It was, yeah, definitely looked rather chilly there. And yeah, I guess I was complaining about it being ridiculous temperatures here. I guess in really hot. And yeah, I guess you had the other end of the spectrum. Someone put up a great image. I tweeted it. It was just a picture of the Earth and the entire northern hemisphere is just this snowball. and the southern hemisphere is just flaming lava. Yep. That was this last week. Sums it up nicely. Okay, well, I just want to start as I usually do with a bunch of thank yous. The list is getting longer, so I'll do my best just to quickly fly through these. So, these are firstly Twitter shoutouts, thanks to TheTypist on Twitter. Twitter. Again, I think they prefer anonymity and that's fine. Also, thanks to Stephen Villiverde, I'm not sure which way it's pronounced. Vic Hudson, Mikulis Dyte, Andreas Ekegeren, Zach Czewiczek, I'm sorry, I have no idea how to pronounce your last name, Zach. S-Z-E-W-C-Z-Y-K. Peter Evans, Beda Kamal, Ben Curtin, Andrew Cameron, Rowan Pope, Nathan Alpay. And also a special thanks to Seth Clifford, who I've been following his podcast called Iterate, which is on the part of the Mobile Nations and iMore stuff with Rene Ritchie and I listen to that regularly. So, it's a little bit of a buzz to get a thanks from Seth. So, thank you for that. Sorry if I've missed anyone. It's been a full on this week and I've been in the midst of changing jobs and I hope I didn't miss anybody. So, thank you for all those shout outs. I really do appreciate it. And there was also one extra special thanks to Maxim Harper. He calls himself a cynical technology connoisseur on his website, which I found kind of cool. And he wrote a very nice review for us in the UK iTunes store. It was very complimentary. So again, thank you very much for that review. Much appreciated. So we also are going to be putting up a poll And this poll will be relatively painful. Oh my goodness. I said painful. Oh no. It's only about seven pages long. And if you screw up at all, you're going to have to start over. Okay. Painless. That's the opposite of what I... Oh God. I need my foot in that, didn't I? Okay. Anyhow, a couple of questions about the units that you prefer to hear things in, metric imperial or metric and imperial. It's a bit of an odd question, I know, but still had a couple of queries from listeners and I'd just like to get a definitive answer from the listeners to see if it's an issue for them or not. More importantly also is we're considering adding live as a feature on the show. However, because of my situation and Ben's situation, we have pretty strict recording hours that we can actually do the show and we can record it. I guess what we'd like to do is see if there's any interest in doing a live show, in making this a live show as well as an edited version, rather like some of the other networks are doing. And I'd like to just get feedback on that and see how much interest if there is any for us doing that. Yeah. And I mean, we're really just looking for if it's something, you know, we're going to put the time up that we're thinking about and if that's going to work for you guys, technically, I don't think we're, you know, we're not worried about the capability of doing it. But yeah, technically it's not an issue. Yeah, right. We just want to make sure that that is something that people actually want and would be willing to take a little bit of time to do. So yeah, absolutely. So obviously if a few people come back and say, oh yeah, we would like it, but then we have a lot of responses saying, oh look, we're not really interested in live, then that's fine. And I just want to get a, see if we we can get a handle on that before we go down that path or not. So you'll see a link to that in the show notes and yeah, feel free please to fill that in, let us know what you think, and we'll assess and feedback the results next episode. All right. So topic for today, Ben. What do we got? What do we got? What do we got? Okay. This is, it's going to sound strange, but I want to talk about noise. And when I say noise, I guess I don't mean noise in the sense of noise in the background of my microphone necessarily or anything else or noise like the kids screaming, which thankfully it's at bedtime so they're all asleep, which is good. But no, I want to talk about noise because noise is a big problem. A lot of people tend to overlook it. A lot of people tend to shrug it off like it's no big deal and/or it's an irritant. And one of the things in my line of work is that you get exposed to a lot of workplace health and safety or occupational health and safety whereby they do a lot of education over good and bad practices by taking care of your hearing because you only get one set of ears. And once they're wrecked, you're out of luck. So it's something that people need to take care of. And when I've done work of the last, well, what seems like a long time, I've worked in different sorts of places like sawmills, for example, bottling lines, brickworks, wastewater treatment plants. I've listed some of these before, but the bottom line is that you walk in the door of these places and on the fence, usually they have the sign of someone's head with a bunch of head ear muff protectors on there. It says hearing protection must be worn at all times. And it's the sort of thing that you don't see as much in an office environment, but there are still issues with vehicles and where you live and the music that we listen to, that frankly, the signs should be everywhere, really. I mean, they're not, but a lot of people just don't think about it. So I guess I wanted to talk about that and what I've learned and what I think people should be aware of. And so to start off, I just want to say from the outset, look, I hated biology. All right. I sucked at biology. So I'm not going to go and talk about the cochlea or the inner ear drum bones or things because I really don't honestly care that much. I feel free to look it up if you'd like. But all I will say is that it's all very delicate. So, you know, let's not wreck it, shall we? So biological content in this episode will be very low. Feel free to look it up if you love biology. I'm sorry, I'm not one of those people. So what is sound? Real quick, just a real high school refresher, real fast. So sound is essentially is a pressure wave that travels through a medium, whatever that medium may be. It could be a solid, it could be a liquid, or it could be a gas, but it needs a medium to travel through so you don't get sound in space 'cause there's nothing for it to travel through. So for the purposes of what we're talking about though, I'm really only interested in talking about sound conduction through air. So that's all we're really gonna talk about today. At a standard temperature and pressure, which is, you know, mean sea level, and I think it's 20 degrees Celsius, something like that, STP. Speed of sound has been measured about 343 meters per second, which is 1,125 feet per second. And that, if you prefer in measurements per hour, that's 1,230 kilometers per hour, or 767 miles per hour. So it sounds quick, but it really isn't. Compare that with light, it's pretty slow really. But in any case, the human ear can, our ears can recognize sound anywhere from as low as about 20 Hertz up to 20 kilohertz. Obviously varies based on the individual, but generally speaking, that's what we come out with. Obviously as we get older, well, maybe not obviously, but as we do get older, unfortunately, the top frequencies tend to roll off. How much they roll off and how far down they roll down to varies again from individual to individual. And obviously, if you've had hearing damage as well, it will also affect it. So, instantaneous sound pressure level is the deviation between the average pressure and the peak sound pressure at a given instant in time. But the actual sound pressure level or what we refer, we'll just loosely refer to as loudness, well, that is actually the the root mean square value of that instantaneous sound pressure level and it's represented in bells. For whatever reason someone decided bells sucked and it would be easier to represent things in decibels or tens of bells. Say everything's done in tens of bells or decibels or dBs, that's what we call them, dBs. So going to do a little more high school math there, It's a logarithmic scale. I don't want to go into explaining that, but just suffice to say, it's not linear. And as you increase in value, the numbers, this actual space on a scale is compressed as you increase in value. So it's a compressed scale as you go up the scale. And it's amazing how many things in nature are logarithmic, but anyway. So sound pressure through the air is most commonly relating to the human ear, so how we hear something. So it's not about the raw sound pressure, it's usually weighted. So what we do is we look at the frequency spectrum between 20 hertz and 20 kilohertz and they developed a curve that they call the A-weighting curve, as in the letter A, A-weighting curve. So the A-weighting curve is specifically designed to fit the human ear insofar as it accentuates the frequencies between 3 kHz and 6 kHz. And everything outside of that region essentially rolls off because that's outside of the most sensitive area of human hearing. And just as a side note, if you would talk previously about things like vocoders and so on in mobile telecommunications, but they also focus on those frequencies. So, specifically in that region, because what they want to do is they want to encode the areas of our speech, the frequencies of our speech that carry the majority of the data or content that the ear hears. So, that A rating, they attach to the end of the terminology. So, they call it DBA. So, you'll see DBA written on all sorts of of different audio devices or sorry, things that create noise. Like for example, the back of your grass cutter, edge trimmer, whippersnipper, brush cutter, whatever you want to call it, it'll have a sticker on the back. For example, the sticker on the back of mine, I think is 87 DBA. And lots of different things, chainsaws again, they'll have them as well. So anything with an engine will have a DBA rating. And in fact, lots of things that aren't engines will have DBA ratings. So the DBA rating is essentially how much noise and sound pressure it's making, and it's adjusted to compensate for human hearing. So why does that matter? Well, the problem is that the human ear is fragile and you can damage it if it's too loud. And you get two kinds of damage. You'll get instantaneous damage and you'll get long-term continuous damage. So the problem is that you need to protect your hearing from both of those eventualities. The one that's most commonly ignored is the long-term high sound pressure levels. So we'll talk about that a little bit more in a minute. Audio, oh, sorry, sound pressure waves travel as an expanding wave front. So usually they have a point or close enough to a point source like a speaker or if it's an explosion, for example, whatever this is causing the sound, it has a single point that it radiates from. And so therefore, because it's an expanding sphere of sound pressure, the pressure will drop inverse to the square of the distance from the source, which is the so-called inverse square law. Feel free to look that one up. Bottom line is that the further away you go, it gets significantly less pressure and less volume. but because it's a logarithmic scale and because our hearing is designed to compress such that it can essentially soften the loud and tweak up the soft so that we hear the softer, the fainter noises. So hearing is designed to do that, which is really cool actually when you think about it. So, we tend to still hear it a long way away despite the fact that the sound pressure is significantly less if you were to measure it. So that's the inverse square law. So distance is a big deal. And another interesting effect is the effect of temperature and specifically ground surface, ground temperature. A lot of people have said, you know, for years, oh, yeah, sound travels further at night. And it does, it does. I actually have measured that. There's two things that cause that. The temperature of the ground, hence the density of the ground and the reflections, although it's not really a reflection, it's more of a guiding and of the sound pressure waves at nighttime because of the colder air above the ground will actually increase the distance that the sound will travel. And that's a rather interesting effect. The other one interesting effect is that at nighttime, things tend to be quieter because less is happening. And when we are, so there's less traffic, there's less people, there's just less of everything. All the birds go to sleep or at least the ones that are sensible do. And yeah, well, anyway, I'm not having a go at owls or anything, but anyway. Anyhow, back on track. Owls are pretty quiet. They are? Yeah. Well, we had a barn owl near our house growing up, and I guess he could be loud, but most of them just swoop in and... Just look at you funny and turn their head upside down? I was going to say they murder your rodents, but... Oh, really? Well, good. That sounds handy, doesn't it? Yeah. Unless, of course, you were having one as a pet, in which case that would be less convenient, I would think. Sorry, Harry, if you're listening, which you're probably not. Anyhow, okay, so, too many in jokes. So here we go. Gosh, I'm sorry, I need to find where I was. Okay, right. So noise interference, so what will happen is noise of different frequencies from different directions will essentially cancel itself out if it's out of phase. So you'll get noise cancellation. And if there's less noise coming in, then there'll be less noise cancellation. So over nighttime, instead of hearing a blended noise which you would hear during the day, you would hear just the specific noise. Like for example, I hear where I live, I hear the freeway over nighttime but I don't hear it during the daytime because there's other noises around that's canceling that out. The temperature is warmer over the ground therefore you don't hear it but over nighttime I do hear it. Anyhow, so that's a real effect that does also happen. So just as an interesting side note, not particularly, not gonna hurt your hearing of a night time necessarily, but anyway. So, there have been a lot of studies. Well, maybe a lot, I think there have actually been a lot. I found a few and there's a few links in the show notes. And they show that for listening to music with the difference between like ear canals and over ear headphones as a noise source is not too much of a difference in terms of how much sound pressure your eardrums will receive. It's more the raw sound pressure level that's being emitted by the headphones irrespective of their type. So the thing that I found fascinating, however, is that one study that I linked to on the show notes looked at iPods, and this is an older study back in 2006, I think it was, or 2005. And the headphones that Apple had before the earpods I think have been pretty well consistent during that time period. So the ones that we had up to a couple of years ago, those older style Apple ear pods, not ear pods, sorry, earbuds, those headphones were tested and with different music players, of course, having different power outputs for the headphones, they were suggesting that anything above 50% volume in your headphones is generally considered to something where you've got to have a time limit as to how long you listen to the music. So anything about 50% of volume could potentially cause hearing damage over a long enough period of time. Obviously, the louder it is, the less time it takes to damage your hearing to the point at which if it was at 100% maximum volume, the listening time was down to five minutes. So you listen to that at full volume for five minutes, you are going to start damaging your hearing. So it's-- - Guess what? - Yeah, I know, guess what, right? - Yeah. - So when I say damaging hearing, I'll talk about what I mean in a minute, but just a little bit more about that. There's been a few independent tests that have been done on the ear pods. And if you look at their response and power and what they generate in terms of sound pressure, they are simply not as loud compared to the earbuds that they replaced. And the reason for that is simple, is they've sacrificed containing the audio inside the ear for a bit of comfort, but they've also provided more, how should I put it? The frequency response is more tailored to a base. So if you've listened to both using ear pods and ear buds from Apple, as I have, and I'm sure many of our listeners have, then the difference there is quite marked, is that the low frequency is far better on the ear pods than it is on the ear buds. And that bears out in the tests that I looked at and I've linked to in the show notes. However, as a result, they do not generate a sum total of as much sound pressure. So they're probably, you know, essentially what I'm saying is that they're softer than the ear buds. Well, and I've noticed they actually they sound better. They both sound louder and the bass level and and well, the broad spectrum sound sounds better. When they're very loosely in your ear, as opposed to trying to really cram them in there like they're like they're in your headphones. Yeah, exactly. Yeah, and I mean, it's they clearly put some work into that because when they are just very loosely in there, it's not super loud, but you do have a give a really good sense of the base there, which is impressive for how small they are. Absolutely. And I've been quite impressed with them. And if my children hadn't have lost them, I made a mistake of lending them to my kids once. And unfortunately, that was the last time I saw them. So someday I hope they'll show up again. Never mind that. That's my problem. You know what's crazy about those two? I know it's kind of an aside, but they do maybe have an issue with earwax buildup, right? Like they get a little gross. And they do seem to... I don't know if they might have faded at all or if it is... I'm not sure. But I was really frustrated with how loud they were one day. And so if you ever do feel like they are just simply too quiet for you to hear, if you swap the left and right side, like switch them around and put them in backwards, much louder, like dramatically louder, which is it's just it's really interesting how much clearly just the that shape that they designed and the porting that they're doing, how what a difference it actually seems to make as to exactly how it's positioned. It's clearly kind of beaming the sound in at a very, you know, very focused direction. So I guess the probably the more sensible thing is just if you're If you're having trouble hearing with your ear pods, maybe move them around in your ear a little bit and find the exact right way to have them in there. I refer back to what you just said previously, which was just before, which was let them sit loosely in your ear because I found that works much more nicely. The design of the ear pods in terms of comfort is significantly better than the earbuds, there's no doubt. the earbuds for even as little as half an hour, I would find my ears were sore. Whereas the earpods, I could wear them for a few hours and not feel any discomfort. I seldom that I would use them for more than two hours at a time with my commute, for example. However, I never noticed that sort of, what would you call it? It's like not an ache exactly, just a general soreness in my ears. So I didn't have that anymore with the earpods. I think I've got pretty small ear holes. And well, I mean, I don't know. That's a technical term. So like having I purchased a pair of the like apples. They have their in ear ones too, which are the canal ones, the canal ones, yeah, which are pretty expensive, but they were actually pretty decent too. And I always had on any of those kind of headphones. I always had to use the very, very smallest ones to even get them in there without having it really have that sort of ache. And some fun stories about getting stuck in there, though. Oh, not good. No, that isn't good. But in any case, a little bit of an aside there, but what I was heading towards is there's an effect that people tend to do whereby you're wearing headphones, in-ear headphones, irrespective of type, whether they're canal ones or they're of sit in the ear canal or whatever. Irrespective, you've got headphones on, but you don't have over ear headphones, if you know what I mean. And as a result, or earmuffs, I guess, as a result, your ears are still picking up external noise, like a reasonable amount of it. Right. So some, some of those are loud conversations, someone else comes in playing music loud without headphones on, whatever the case may be, loud traffic, I don't know. And you turn the volume up on yours to try and compensate. And that's That's where it all starts to go wrong because normally you'll listen at a volume level that's acceptable. It's when external factors come into play that you then crank the volume. And as soon as you start cranking that volume up to compensate for external sounds, that's usually when you're crossing that 50-60% mark. That's usually when you're going to start doing damage. And that's when you've got to take yourself out of that environment and go to a quieter environment. If that's not possible, then honestly, you should be looking at different headphones. And in that case, of course, noise cancelling headphones are your best option in that case. If you're in a really noisy environment, the answer is not to crank it, it's to get noise cancelling headphones. And I know they're expensive and I know they go over your ears, but believe me, it's a better option. So in any case, so why I talk about damaging your hearing, okay? And I've got one word for you and that's tinnitus. Now there's more than one way to damage your ear. I mean, apart from shoving a screwdriver in it. It's just tinnitus is the most common and I'm going to put my hand up right now and say that I actually suffer from tinnitus. That's one of the reasons I want to talk about this is because it's a subject that sort of hits a bit close to home for me. My tinnitus that I have, okay, before I get into that, so what is it? There's actually two different kinds of tinnitus that's generally considered. got objective tinnitus, which is essentially driven by a mixture of different causes like muscle spasms causing clicking or crackling noises in your ear. A subset of that is pulsatile tinnitus, which as the name might suggest, pulsatile is to do with the pulse and that's caused by increased blood turbulence or blood pressure in and around the eardrum. It can be indicative of hypertension. So if you have high blood pressure and you're not aware of it, that could be a giveaway that perhaps you need to see a doctor and just get yourself checked out. Having said that, that's not the focus of the tinnitus that I wanted to talk about because that's actually, as the name suggests, it's objective tinnitus, not subjective. Subjective tinnitus is essentially there all the time for a bunch of different reasons. So you've got conductive, sensor and neural, and those essentially are the two causes I wanted to explore. There are a raft of other potential causes for tinnitus, but I'm really just focusing on the ones that are more easily preventable through controlling the noise in your environment. So we'll stick with that just for this discussion. So I acknowledge, yes, that there is a whole bunch of other causes, but I don't want to explore those at this point. So. With those causes in particular. Physical damage to your eardrum or ear canal, the obvious one is physical damage due to object insertion. Oh, insertion. What was that they said? Don't stick anything sharper than your elbow. Nothing smaller than your elbow, right? Into your ear, right? And whilst I cannot imagine contorting my elbow to reach my ear for one thing. Yeah, okay. Who hasn't put a finger in their ear at some point? At some point, you clean out the earwax in your ear somehow. And you have to be incredibly careful how you do that because physically touching the eardrum will cause damage to it if you are not careful. So, That's the obvious, obvious, obvious one. And also obvious one that's also easy to prevent is ear infections. And most ear infections that are not caused by a secondary illness, like for example, it's like a secondary, sorry, it is the secondary illness. Let's say you have a sinus infection and that travels to the inner ear. Well, oh dear, I guess we're lucky at the moment. We live in a world where we've got lots of antibiotics and antibiotics can cure so many of our ailments for the moment before superbugs get out and scary stuff and let's not go there because biology. Anyhow, bottom line is that ear infections, however, are most commonly caused by people going swimming and water getting lodged in the ear and that water not being removed. A lot of people don't realize when there's water stuck in their ear. I've done a lot of swimming and I guess this is something that in Australia, it's actually quite common for people to go swimming quite regularly. Most Australians, they had to swim because we live really close to the coastline because you go too far inland and it gets a little bit less hospitable, shall we say. When I was living in Calgary for a few years, I became acutely aware of the fact that it's inland and whilst it may be near a few lakes, a lot of people don't know how to swim and a lot of people don't actually go swimming. If you are swimming, you're swimming in a chlorinated pool. Oh, sure. But I mean, even chlorinated water can still give you an ear infection. So this is the problem is that if you do go swimming, it's far less often. People for example, are far more likely to be into skiing or into ice skating, that sort of thing rather than swimming. I was staggered by the number of people that just didn't know how to swim. I imagine the same is true of most states or places in the world where you don't live near large bodies of water. It just makes sense. In any case, this may not apply to a lot of people. This is why I'm saying this. If you're someone that doesn't regularly swim, then whatever. That's fine. Don't sweat it. But all you need to do is put ... They're usually based on a very low concentration alcohol and you simply put a couple of drops in your ear and the water comes out and hey presto you're all good. Recognizing you've got water in your ear helps. And again, hey, why do I bring that one up? Well quite simply, my daughter had an ear infection last week, literally, and she's just finished a course of antibiotics to clear that up. So, if you leave that unresolved, that will also cause long-term hearing damage as well as hurting like hell. So you know, and affects your balance as well. So all that's all well and good but that has nothing to do with noise. So okay, just want to cover it, let's move on. So noise, essentially there's two kinds. There's the, what some people refer to as acoustic shock or impulse noise or ongoing exposure to loud noise. And I touched on these briefly before, so in a bit more detail now. So physical damage to the eardrum caused by impulse noise. Well, what that means is that the ear, the ears, the nose and the eyes are all connected through eustachian tubes. I hope I'm pronouncing that correctly. Again, biology. And those tubes equalize the pressure between them, but they don't equalize it instantaneously for most people. So, when you go up and down in an elevator in a really tall building or up and down a tall hill, a big hill, or when you're in an airplane, then you're climbing or descending. All those times, the pressure will equalize. Usually if you swallow and it creates a brief movement in the eustachian tubes and it allows that pressure to equalize from the inside to the outside of your head so you don't get that discomfort in your ears and your eyes. A lot of people have this. Some people seem to have tubes that react relatively quickly, but for me at least and most people I know that's not the case. So it kind of sucks, but that's just reality. So when you get a large sound pressure wave hit your head, and obviously not physically hit, arrive at your head, then the amount of pressure outside your eardrum is dramatically higher than that inside your eardrum. And that difference in pressure is going to cause, if there's a high enough sound pressure, will literally cause your eardrum to rupture. So if you're standing next to or nearby an explosion, assuming the pressure away from the explosion doesn't kill you, chances are your hearing is going to be, your eardrums may be ruptured or you may suffer some form of hearing damage. And that's why in the movies you'll see, at least these days anyway, they're trying to make things more realistic these days than they were about 50 years ago. But the hero dusts himself up off after an explosion 50 years ago and says, "Oh, I'll I'll just get the gun out and I'll chase the bad guy. Yeah, okay, no, you're gonna stagger up. Your hearing is gonna be ringing. You're not gonna be able to walk in a straight line. You know, anyway, nevermind. Point is, that's really bad. And that can have not just short term, but obviously long term consequences. So mind you, if you're standing next to a bomb and you survive, maybe that's the least of your problems. So hey, you know, you survived, right? - Right. - So I'm gonna have some ringing in my ears, but I'm alive. Anyhow, again, not the focus of what I want to really focus on. What I really want to focus on is the long-term damage caused by an ongoing sound pressure. And just out of curiosity before I finish with the impulse noise, sound pressure levels ranging between 160 dB and 195 dB, they've been quoted as being the level at which a rupture will happen. Obviously, it depends on the individual. Depends on the interconnecting tubes in their head, the size of their eardrum, blah, blah, blah, blah, blah. It's individual. but on average, the numbers varied significantly. So I looked around on quite a bit on this and I always thought it was just 160, but I found a couple of articles that said, no, it's actually as high as 195. Frankly, 200 dB and you're supposed to be dead. So I tend to believe the 160 figure, but in any case, it's down to the individual, as is usually the case, but in that sort of a range of sound pressure, and that's quite loud. So there is a link in the show notes that shows you lots of the different levels and what they are, like 30 dB is a whisper and 60 dB is a normal conversation, that sort of thing. So feel free to check that out as well, give you an idea of just how loud 160 decibels is, it's louder than a fighter jet taking off, so that's loud. Okay, but ongoing exposure from some sources as low as 70 dB, but probably more accepted figure, 85 dB, again, depends on the individual. If you're operating, for example, my, the whipper snipper I use is 87 DBA. So definitely, definitely that's going to cause hearing damage. So if you have continuous exposure to that noise level over a certain period of time, it will damage your ears and you'll begin to develop over a long period of time, the effects of tinnitus. And that's what happened to me. When I was a kid, I listened into a lot of loud music, essentially. And yeah, I would crank it up rather loud and yeah, that was rather handed up, very stupid of me. Yes, thank you. There's no telling a teenager or anything, right? And I was one once and yes, I also heard the warnings from certain people, but it wasn't until I started in engineering that I started to take it seriously. Unfortunately, by then the damage had been done. And as I started to develop this noise in my hearing, at first I ignored it. But now I realize what it is. It's like, "Oh, great. I'll just rewind the clock 20 years ago and I'll tell myself to turn the damn music down." Yeah, I did the same thing. My right ear is burned out pretty good from playing guitar in terrible vans. And just the way I stood, the way I practiced all the time, it would always be right up by, you know, for a few years a half stack and that'll do it. Yeah, well, that's right. I mean, because, yeah, you're in a band for quite a while and that's intense, right? I'm surprised I haven't had any tinnitus, but yeah, it's definitely, I just do not hear as well out of that ear anymore. It's noticeable, right? I mean, I wouldn't say it's bad. just I can tell. Well, that's a big problem for a lot of musicians. And honestly, that's occupational noise, right? I mean, the right answer would be, yeah, you should have been wearing hearing protection up on stage. But I think the thing that I find is that there's this stigma to it. It's like, it's not that loud. What are you doing wearing those bright orange earplugs? We actually we usually would when we were when we play on stage. But, um. Oh, we. This is it. Practicing. It was still just, you know, is it spending? I think even without having things be really cranked up. I mean, if you're playing guitar, if you're playing like guitar and the kind of like bands we were playing, it requires volume. And even if it's, you know, even if you're dampening things down, you're still. you're still regularly hitting up to those levels without going even to the insane level of a show. Yeah, absolutely. And rock concerts, for example, were listed coming in between 110-120 dBA. So that's quite loud. And obviously that's going to cause hearing damage over a long period of time. So in any case, tinnitus, and I've got again links in the show notes, have a look if you want to look in depth, but for those that don't have it, that want a description of what it sounds like, it's like a very faint white noise, similar to a TV tuned into a channel that's just static, but with the volume turned right down. It's not loud, it's just, Well, I think for some people, perhaps it is loud, but it's when there is quiet, like, for example, I've got headphones on when I'm recording this and I can hear it because the headphones are blocking out a lot of the external noise. But it's the sort of thing that when you're concentrating on something else, you don't notice it. It's only when everything is quiet that you then notice it. And for some people, it's maddening. For me, it's just like, okay, it's annoying, but oh, well. Is it like a broadband, like a white noise, is pink noise or do you get a tone? It's kind of a white noise sort of thing. It's slightly higher pitch. It's not a low frequency thing. So it's just like a high whining sort of noise. But it is very faint. And it's the sort of thing that once you've identified what it is and you can hear it, you can't stop hearing it. And if I'm busy and distracted and doing other things or listening to music or whatever I'm doing, then I don't notice it. It's not there. It's not a problem. - Right. - It's only when it's really quiet that it's an issue. And some people with tinnitus say that listening to music, whatever else, 'cause it's sort of, you know, I find that ironic. The listening to music to drown it out is in essence using the thing that gave you the tinnitus. Well, in my case anyway. - The hair of the dog that bit you. - Something like that, yeah. The irony is not lost on me. But in any case, it doesn't affect me that much. And there are people out there, but the statistics state that up to 15% of the population is identified as having tinnitus, developed tinnitus at some point in their life. And that's a lot of people. And of those, they say one to 2% of that subset, it's so bad that it's a condition, it's a serious condition that they need to manage somehow. There's no medications for it. There's nothing you can do. You can't just pop a pill and it goes away. There's all sorts of other different, I don't want to get into the treatment for it. I'm trying to identify this causes for people so that they don't go through that. And that they can take some kind of active steps to prevent that for them. So, you know, hey, stupid me, I was once and I learned my lesson. Unfortunately, I don't get a second set of ears. So anyway, all right, just going to move on then. So noise sources. Now, most people that are listening to this probably live in a city environment or if they don't live in a city environment, they may work in a city environment. So I thought it would be worthy to discuss some noise sources there that a lot of people take for granted or ignore. So the first and I think biggest one in large cities are freeways. And people think, oh, you know, cars noisy, right? It's just like as loud car engines and certainly there are loud car engines making noise, but it's actually not the engine that's the problem, it's the tires. - Yeah, it's the tires. - It's the craziest thing. So you've been driving a Tesla Model S, it's essentially silent except for wind noise and tire noise. And the funny thing is that you can insulate your car, you can stop the noise from getting into the car by putting layers of soundproofing and so on. And that's what they do. We'll talk about that in a minute as well. But inside the cabin could be whisper quiet, but you can't shield it as easily on the outside. No one puts an acoustic cover on the car. It's all open, right? So as the wheels are going onto the tarmac, away they are, they're just generating noise. And it's just all out there, radiating out into the world. So what's interesting for me though, is something that I learned a few years ago, is that there's a big difference between asphalt or otherwise known as bitumen and concrete surfaces. And concrete in terms of its durability is much preferred as a freeway construction material because it is far more robust, lasts a lot longer, maintains its smoothness over a long period of time. Yeah, there are all sorts of pluses. The biggest downsides are it's expensive to do it. But obviously, you recoup that cost long term because you've got less maintenance costs. However, the other one is the noise. And the concrete can be between four and five dB louder, tiler noise for the same vehicle compared to the same vehicle driven on asphalt, bitumen. And that, you may say four or five dB, oh, well, yeah, that's four or five dB, right? That can make a big difference because the whole inverse square law that we're talking about, sound radiating out as a wave, that can make a big difference. So instead of it being, if you've got a row of houses just next to the freeway, then that sound will not just hit the first two or three rows of houses, that will be loud enough to cause issues further back. Like it could be a whole block back because of the different material for the pavement. So yeah, that's a big issue. And so of course to combat this, what they do is they build sound fences. So you'll see typically the good ones are made out of concrete, cheaper ones are made out of wood and the really cheap ones that don't do so great are made out of steel or like corrugated iron or that's it. Each of them have different sound absorption and reflection properties. The idea is you build a freeway and these days it's just a given because most freeways are going in between wherever residential housing is and that's where you'll see the fencing and that's designed to stop the noise because otherwise, living in a house next to a freeway with cars going by generating like 95 dB of noise, that's not good. So, interestingly though, as I said, inside the vehicle is a different story. And back in 2011 in Europe, a magazine did a rather interesting test of a bunch of different cars to find out which car had the loudest and which car had the quietest internal noise levels. So for those people who are fans of BMW, congratulations, at 58 dBA, they had the quietest cabin at 100 kilometers an hour, also known as 55 miles an hour or thereabouts. The loudest car that was not a sports car, I just want to point this out. I took cars out of the list that were not sports cars. I'm like, "Come on." If you're buying a Lamborghini, Aventador, Murcielago, or a Ferrari, whatever, those ones are designed to have a loud engine that's supposed to melt your heart. And frankly, I can feel that to a point. But at the same time, it comes with the noise as well, right? They say, "Have a noisy engine because it sounds lovely. Oh, by the way, it's loud." Right. Oh, yeah. Okay. I remember a reading that in, I think it was the Countach, I think it was, it had such poor sound shielding that people would say that they would drive them with earplugs. And the Ferrari F40 or F50, I think it was the one that was stripped down, you had to wear earplugs in the thing because there was no acoustic shielding. But anyway, So this is the not a sports car, loudest interior was actually a, I hadn't heard of this one particular one before. It's a Lada Niva, 1.7i Hunter, which is a four by four, 77 dBA in the cabin. Ouch. Yep. I wouldn't like to be driving in that car. Now, obviously that's what the windows up, you know, windows down air turbulence, and so on. I don't, I, I didn't go to that depth, but I'm sure there's other studies that show you the sound difference, having the windows down, windows up and the air conditioning running and so on. But in any case, the inside of the car, typically you're okay, typically, but some of the cheap, some of the, well, I was going to say cheaper, but some of the, there are louder cars out there and honestly, you know, I don't understand the need to have a loud engine noise in the cabin. I just don't get it. So anyway, On that sort of vein, what about motorcycles? Because there's actually, I have a couple of mates that ride motorcycles around. And one of the worst offenders are those ones by Harley Davidson. And they specifically design their motors to be loud and their exhausts to be loud. - And that exhaust note is, well, not patented. Well, is it patented? - It probably is. - It has the irregular firing order. - That's right. - 130 degrees, something like that. Yep, that's right. Yeah, it's their signature noise. It's like you hear that putt putt putt sound. I guess you can tell what I think of it, but never mind. The point is that it's very distinctive. It's their calling card and it is loud up to 120 decibels. I think it is. There's a couple of things I've linked to in there. It's quite loud. So you don't, if you're going to be, if it's going past you, it'll annoy you, sure. But this is more about if you're riding a motorbike. So again, a link in the show notes to the effects of noise if you're wearing a helmet, which of course you should be, and there are also tests done if you weren't wearing a helmet, but I was thinking at the time, how many people in how many countries are illegally allowed to ride a motorbike without a helmet on? And even if they weren't legally allowed to ride a motorbike without a helmet on, why wouldn't they be wearing a helmet? Just makes me think of Lawrence of Arabia, and it's like, yeah, it didn't work out well for him. Yeah, helmets, please wear helmets when you're riding a motorcycle, everybody. Anyhow, okay, so the problem is that if you are riding on them, the variance of how long it would take for you to get hearing damage on the loudest motorbike, which I think the last one I tested was a Harley, then you'll start to get damage even with a helmet on within 60 seconds. You'll get permanent hearing damage within a minute. And if If you drive for a different bike, like they had a, there's a BMW in there, there's a Honda in there. So yeah, not necessarily sports bikes, but just run of the mill average motorbikes. I'm not a motorbike guy. So you know, motorbikes. They're loud even when you're in neutral. I mean, it's just, you're getting, and those are noisy tires too. And you get a lot of sound on a bike. Absolutely. But I mean, their best case scenario was 45 minutes and that was on a much quieter bike. And of course, that's driving it at highway speeds and all that other good stuff. So you've got wind noise in the helmet, you've got tire noise, and you've got engine noise, all that thrown together and, oh dear, you should be wearing hearing protection. And a mate of mine did work on my most recent large project about a year and a bit ago now, actually, time flies. And he would ride his motorbike to and from the pump station where we're doing some programming and he would get off his bike and he'd say, "Oh, hey, John, how's it going?" And I'd be like, "Hang on, I've got to take my hearing aid thing out." He was a good boy. He wore his inner earplugs and everything. After I'd made that mistake a few times, I was sure to wait for him to physically remove the earplugs before I spoke to him because he couldn't hear me. He was smart about it, which is good. In any case, so that's motorbikes. Now, another thing that I wanted to mention, which is strictly speaking not a hearing damage thing, but I still think it's fascinating. And I went through this and goodness me, this is noise used as a defensive mechanism. In other words, a security system that's designed to incapacitate you using noise. Have you heard of these things? Have you watched whale wars? I have not. The Japanese whaling boats put them on their ship. They can be used as an offensive weapon too, not just defensive. You can, it's less than lethal weapon. They're crazy. It's just, well, you can describe it, I'm sure. Well, the situation that I was in is that I was working on a defense project and they They take their security very seriously, rightfully so. And the building that I was in, I hadn't been working there for very long and didn't fully understand all of the rules about evening lockdown. But after five o'clock, what they used to do is they used to change the swipe card access for travel between floors and they would turn it off. So essentially, the way it would work is you had, and I guess this is these days, and I these days, this is over 15 years, about 14 years ago now. So back then, it was more or less accepted practice that if you didn't take, if you're going one or two floors, you take the stairs, you don't take the lift for one or two floors. That's fine. But these days, they say, you know what, you don't take the stairs at all. The stairs are solely for fire escape purposes only. That's it. But back then, it was still considered standard practice, if you want to skip between one or two floors, you just take the fire stairs, no big deal. The stairs are such that you don't need a swipe card to get into the stairwell, but you need a swipe card to get out of the stairwell. If I was going between two floors, I could open the handle and open the door and walk in, go up and down the flight of stairs as required, swipe my card and then get in to the next floor. Pretty standard stuff. What I didn't realize was that after five o'clock, there was a disabling of that system and they enabled the security system such that if you entered the stairwell, the fire stairwell, then the sound incapacitation alarm would go off and the stairwell would go into lockdown and would not let you out. And that was a painful lesson to learn, I must confess. It was horrible. 125 dBA and it's a set of rapidly oscillating frequencies. And I was all right, trapped in there for the first minute. It didn't seem to get to me too much, but then you start to feel a little bit disoriented and I started to feel very nauseous like I was going to throw up. That's what they do. And by the time the security guard actually was able to release the system, pull me out and scream at me, I really wasn't feeling all that crash hard. I'd broken out in the cold sweat and I felt pretty horrid, pretty wretched. So yeah, just as a side note, yeah, if you're ever working in an environment like that, please check the rules between going between floors after hours. Did you already have the tinnitus before that? I hadn't noticed the tinnitus at that point, but no, I don't think I can go back and sue the defense department. Interesting idea if that's where you were going. Well, I was just saying. I don't know. I never thought of that. Sometimes I'd feel sick after playing guitar, but not for that reason. Okay. Yeah. So anyway, I just thought I'd share that little anecdote there. It was quite an unpleasant experience. Well, that's what these sonic guns basically, though. They... you point them at a crowd or whatever, and it will make you nauseous. Like, tremendously so, and enough to kind of knock you on your knees. Yeah, that's it. And that's the idea. Yeah, and they say, "Oh, yeah, no long-term damage." It's like, "Well, yeah, you hold that on someone for five minutes and, yeah, there was actually long-term damage." Anyway, so talked a lot now about all the different sources of noise and, yeah, there's a lot more. Obviously, if you live near an airport, if you live near a train line, if you, you know, and so on and so forth. But by and large, that's a lot of the ones that people don't think about that I've mentioned. And yes, there's more, but rather than going about that forever, let's just talk about something a bit more practical, which is the point of the show is I wanted some people to walk away from every show wherever I can with something practical that they can apply and consider for their lives day to day. Things that, hence the name of the show, Pragmatic. So I'm trying to focus on that. So how do you protect your hearing? Well, obviously hearing protection, yeah, but there's multiple kinds. So the obvious cheap ones are the disposable inner ear plugs and they're made of an expanding foam and you just roll them in your fingertips, insert them in your ear and just hold them in there for a second and then they will expand to basically cut off all of the access ports into your ear canal. And those inner ear plugs are essentially disposable. They're disposable because that ability of the foam to be compressed and then expand is diminished with every time you compress it. So if you take them out and then try them again the next day and recompress them and put them in your ear, they won't expand out to as full as they were the previous time. They seem like they're a little bit temperature sensitive too, right? Yes. They'll get really soft and malleable. That's right. In hot conditions. That's absolutely right. And a lot of places like those because they are cheap and they're essentially easy to dispense. For example, a lot of industrial sites that you go to, you'll walk in the door and as you're going out of the workshop area, there'll be a dispenser and you can, some of them, you turn the handle at the bottom, other times just pull out a little plastic packet and you open it up and you've got two of these things in there. And yeah, they're cheap, they're cheap as chips. So, and they do provide pretty good protection for most environments. But they are considered entry-level protection though for most applications. And they're also discrete. So, from a distance, you know, most of them will just poke out of the ears just a little bit, you're not going to see them like you're going to see over-ear earmuffs. You can also get reusable ones. And the reusable ones are more like a series of increasing concentric circles or concentric discs if you sort of follow my meaning. There's a few links in the show notes, you can have a look at different ones. And these ones tend to, you know, all the usual problems with reusable ones, you tend to get buildup on them, they become less effective over a long period of time and you've got hygienic problems. I remember I worked at a coal mine for a while and one of the sparkies had these ones he particularly liked. They were an unusual color. I think they were blue, sort of a strange blue color. Yeah, it was unusual. Anyway, most of them were orange or yellow. I noticed that the tips of them were coated in black. It's not black from the coal dust. It was actually black from the carbon brushes on the drag lines. So they're changing out the carbon brushes every so often. But that's the problem is whenever the machinery is off, you don't have to have them in and they drape around your neck. It's typically the way you do it through your collar. And as you lean forward, there's enough length on that thread that they actually dangle in whatever you're doing. So it's kind of like the tie clip problem. So there's no earbud clip. And so when you shove that in your ear, of course, you're shoving all that soot into your ear canal, that's probably not hygienic. In fact, it's definitely not hygienic. People tend to report from the non-disposable ones, no matter how much they are, essentially in the long term cheaper and they can be customized for your ear. They tend to cause hygiene problems longer term. Another interesting one that I've come across just once in real life is something called a Zwizloki ear muffler. This one's kind of weird. What it is, is it's essentially, it goes in your ears like a set of headphones, but it extends the ear canal sort of up the side of the support for each of them, because it's like a set of headphones over the top of your head, right? So it extends the ear canal up the sides and towards the top of the head. What's weird about that is that it reduces the amount of capture area that the sound waves can travel through, and the way they design the canals, it basically attenuates of the worst frequencies that can cause the most damage such that you can literally save yourself. You can still talk to people and hear them clearly, but have the worst frequencies attenuated. Right. That's clever. Fascinating. Yeah. Yeah. Fascinating idea. I've only ever seen one person wearing them and my first reaction was, "What the hell is that you've got on your head?" Yeah. It kind of looks like someone out of Star Wars. Yeah. Yeah. That's, yeah, exactly. But you know, in any case, uh, I've only ever seen them once in, in golf. It looks like a lot of hunters and, uh, I guess they're popular for, for shooters. I'm looking on Google image search and half the stuff I'm seeing are guns. It could well be. Um, and in any case, some people call them Zems, but, um, in any case, these things are a little bit rare and they're a bit more expensive, but yeah, they give you a, um, an interesting result. The other most popular kind, and I'm just covering the most popular kinds that I've seen, is the over-ear hearing masks, which of course were the originals. And the thing is that these ones, they completely enclose your ears, just like a full over, you know, fully enclosed headphones, right? They provide the best possible protection pretty much over the entire frequency range. But the problem with that is that they're very uncomfortable, especially in hot conditions and long periods of time. And they're also the most expensive. There are also a problem for people like me that wear glasses, because what'll happen is the bands on the side, the supports on your glasses will cause a break in the seal, and you break that seal around the skin and that lets sound in, and that reduces their protection rating. So, you know, it's okay if you're wearing contacts, but there are also sites where you have to wear protective safety glasses. So, you know, I go and put on contact lenses, and then I ruin it all by putting on safety glasses. So it's an interesting balance when you're doing personal protective equipment for hearing and when you've got to mix in all the other options as well. So if you have a look at these, each of these are given a rating and each country writes them differently, but there's essentially three standards. There's the American standard, which is called the NRR, which is the noise reduction rating. There's a European one and an Australian one, but we'll just focus on NRRs for the moment because, you know, North American standard is actually quite commonly used around the world. It's just that in Australia, we've got an additional standard. You'll typically see both of them written on the box. So you buy a box of earplugs or a set of earmuffs, you'll see both the ratings on there, see the NRR and you'll see the different rating as well. So there's a good link in the show notes about that if you want to look at the differences and why it is the way it is. So anyway, when you look at the NRRs for these things, it's quite surprising that the ear plugs and the over-ear head muffs appear to be very similar in their ratings. What it doesn't give you an appreciation for though is the frequency ranges that they protect you against. So for example, over-ear ear muffs are going to give you far better protection on lower frequencies. And that's because it's blocking out the entire lobe part of the ear, whereas the inner ones will not block out that direct compression. But because your ear lobe is still exposed to the sound, that will conduct some of that sound into the ear canal, lower frequencies anyway. And when I worked at, did some work at a sawmill and anyway, when they went in there, I didn't have over ear head ear muffs. Gosh, hearing protection, you know what I mean? And when I walked onto that site, they said, I'm sorry, that's not acceptable. You have to go and get these specific ones that are rated for these frequencies. And I'm like, okay, fine. So I went and I got some of those and came back because the inner ear ones were simply not acceptable. You can also double up and double your money. And because it's a logarithmic scale that I don't add together, but if you put earbuds and then you put the earmuffs over the top, you will get essentially not quite twice, but you'll get almost twice the level of protection. So instead of blocking out 27, let's say, dB, you'll block out 39, 40 dB. You got to add your logarithms together, but you know, that's high school math. Go and do it if you want. Just trust me Okay So finally My advice is in my particular use cases where I when I was younger I Will confess noise cancelling headphones didn't exist really when I was a kid when I was teenager They came out shortly thereafter and they were hideously expensive And I think Bose or was it Bose? I think it was Bose the ones that came out with them originally. I think so. Yeah. If not, they were done very quickly. Yeah. And the noise cancelling works by essentially listening to the outside noise, shifting it out of phase and then cancelling it noise such that you don't hear it on the inside of the headphones like an active noise cancelling technology. Right. Very cool stuff. However, it's not cheap. And although it's come down a lot in price, I think there's still several hundred dollars for a pair. But honestly, I think it's money well spent because either that or you'll be forced to crank the volume up whenever there's something loud going by and you just won't hear it. You'll have to crank the volume up or you can't hear it or you have to give up listening to whatever you're trying to listen to. Whereas if you've got noise cancelling headphones, it won't matter. It'll still be a nice, serene, quiet environment inside those headphones. So that would be my advice. If you do listen to a lot of music, honestly, or a lot of podcasts or whatever on public transport, that's what I would be doing. And I'm not saying that if you don't do that, that you will get issues with your hearing later on. Obviously, if you're careful how loud it is, then that's one thing. But in my particular case, I wish I had taken more care when I was younger, when that damage was being done. If you want to talk more about this, you can find John on Twitter @JohnChidjy. Same on App.net, and you should check out John's site, techdistortion.com. If you'd like to send an email, you can send it to [email protected]. I'm Ben Alexander, and you can reach me on Twitter @fiatluxfm. You can also follow Pragmatic Show on Twitter to see show announcements and other related materials. We'll be putting up that poll on the website and we'll be tweeting links to it as well. We can talk about the conversions and whether or not you guys want to do a live show. I think that's it. Is that it, John? I think that is. I'd just like to say a final thank you to all the feedback we've been getting. It's been fantastic. Keep it coming and I'm just glad that everyone's enjoying it. So Thank you so much for listening. All right. Take care. You too. [MUSIC PLAYING] [Music] (dramatic music) [BLANK_AUDIO] [BLANK_AUDIO]
Duration 1 hour, 7 minutes and 31 seconds Direct Download

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Ben Alexander

Ben Alexander

Ben created and runs Constellation.fm and Fiat Lux

John Chidgey

John Chidgey

John is an Electrical, Instrumentation and Control Systems Engineer, software developer, podcaster, vocal actor and runs TechDistortion and the Engineered Network. John is a Chartered Professional Engineer in both Electrical Engineering and Information, Telecommunications and Electronics Engineering (ITEE) and a semi-regular conference speaker.

John has produced and appeared on many podcasts including Pragmatic and Causality and is available for hire for Vocal Acting or advertising. He has experience and interest in HMI Design, Alarm Management, Cyber-security and Root Cause Analysis.

You can find him on the Fediverse and on Twitter.