Ask Slashdot: Hacking Urban Noise? 474
b1tbkt writes "I live at the corner of one of the busiest intersections in my city (pop. 350k). Although I've replaced all windows, insulated, and caulked every square inch of the place, the fire trucks and cars with obnoxious stereos still regularly intrude on my home office. Most of the noise comes in through the windows. I'm considering mounting an oblong parabolic reflector in the ceiling above the windows with a steady feed of white or brownian noise directed into it (e.g., via a small speaker placed within the reflector) to create a 'wall' of sound that would act as a buffer to the outside world. Active noise cancellation would be nice, too, but that's probably more than I want to take on. I don't see any products on the market for this sort of thing. Does anyone have any experiences to share with similar homebrew noise remediation efforts?"
How about a shrubbery? (Score:2, Informative)
I think the problem is that you've only focused on the building. It's more effective to stop it before it even gets to the building.
Heavy drape (Score:5, Informative)
Have curtains made from the kind of heavy drape they use in studios. Check out how people deal with acoustic treatment in home studio builds. For instance the gearslutz.com "studio building/acoustics" subforum has many threads to geek out on.
Mass (Score:5, Informative)
Although there are dozens of vendors selling what sound like promising solutions, there is only one solution that really works: more mass. Think of it as a physics problem.. sound waves energy transmitted through the air that cause parts of the structure (including the structure above and below) and environment (e.g. the air around you) to vibrate at a particular resonance. The only way to stop the noise is to stop the vibration. A popular option is to use double drywall with something like rockwool insulation between the studs. You can get away with either 2 x 1/2" drywall or 2 x 5/8" drywall with a small furring strip in between without sacrificing too much living space. Look into Green Glue as an additional way to dampen vibrations in that setup. You can also go for a detached wall or "room within a room," but that starts to get expensive to do right.
If you want to look at a "serious" solution ($$$$), you should try to find a sound mitigation contractor in your area. They can survey the room during different times of day and determine what the best solution is for your situation.
More details needed (Score:5, Informative)
How and what, exactly, have you insulated, and where is your domicile in relation to the street?
Do you have sound dampening mats on the ceiling? If not, bear in mind that most houses and apartments are above street level, and most of the sound will be reflected off the ceiling. A layer of sound dampening material there should have the largest effect.
If you live low to the ground, sound insulating the walls that can see the street, rather than just outside walls would have a similar effect.
A few strategically placed plants or sound dividers - think cubicle walls but far less intrusive - can also help.
If you must go with a noise generator (which I don't recommend), try pink noise instead of white. The sounds from the street you try to mask out are going to be mostly low frequency, and white noise will mainly add more sound energy in the higher end of the spectrum.
What, specifically, did you do? (Score:5, Informative)
Although I've replaced all windows, insulated, and caulked every square inch of the place,
I've been in houses on a busy streets where the street noise stops at the walls and windows. So, possibly, you did not go far enough. For example, there are windows and there are sound-reducing windows. [soundproofwindows.com]
Maybe you need to re-evaluate what you did to keep the noise out before you embark upon a project to reduce or mask the noise inside the room.
Build another wall (Score:5, Informative)
You will be surprised at how effective this is while leaving the original "look and feel" of the room.
Can't recommend noise canceling headphones (Score:4, Informative)
One of the last things I've ever bought from Sony were their ultra-expensive MDR-NC500D digital noise canceling headphones. I can't speak for other noice canceling headphones, but can definitely not recommend the ones by Sony. Don't get fooled by the advertisements, the actual noise canceling is pretty weak, does not have any effect on car noise, and is only noticable when you listen to music. (You can't use them just for canceling outside noise.) Moreover, they need power all the time in order to work at all. In my opinion, they are definitely not worth the money.
Wall of sound won't work (Score:5, Informative)
Barring that, noise cancelling headphones or double-pane windows, as others have mentioned, are going to be your best bets. And double-pane windows are good for heating/cooling anyway.
As an aside, I'm also rather skeptical that noise cancellation for the entire apartment could ever be practical. The problem is the waveform bouncing off the various walls and other features of the apartment is going to be too complex to accurately measure or cancel. And then what about the sounds you do want to hear?
Re:Get a Pair of Headphones (Score:3, Informative)
Re:are the windows.. (Score:5, Informative)
We put all triple-pane in our house (Winnipeg, Canada) 5 years ago. We noticed the street noise almost disappear. (Not to mention the winter heating bills dropped by ~30%+)
Cost a pretty penny, about $13K for the whole house, but man was it worth it.
It's not legal (Score:4, Informative)
Re:More details needed (Score:1, Informative)
Do you have sound dampening mats on the ceiling?
Pet peeve:
* damping - removing energy from a system
* dampening - making wet
Do a measurement first!!! (Score:5, Informative)
Next compare the attenuation offered by each possible solutions (noise attenuationg windows, wall insulation, etc.) against the attenuation you need to achieve. If it isn't enough, move away, otherwise try installing the best solution you can afford.
Noise should be stopped before it enters the walls of your home: Once it is there, it can follow unsuspected paths to reach your ears (pipes, wall joints, etc.). The best way to stop it is to increase the acoustic impedance [unsw.edu.au] of external walls and windows.
Attenuation could be increased using viscoelastic materials like rubber: however they are best for attenuating high frequencies.
Re:Get a Pair of Headphones (Score:4, Informative)
Wrong. Headphones DO block noise, if they look like these [sennheiserusa.com].
No, earbuds don't block noise, but those aren't "headphones".
Re:More details needed (Score:5, Informative)
How and what, exactly, have you insulated, and where is your domicile in relation to the street?
Do you have sound dampening mats on the ceiling? If not, bear in mind that most houses and apartments are above street level, and most of the sound will be reflected off the ceiling. A layer of sound dampening material there should have the largest effect.
If you live low to the ground, sound insulating the walls that can see the street, rather than just outside walls would have a similar effect.
There are two components to the noise intrusion - the direct field and the reverberant field. Adding absorptive finishes to the room will help reduce the reverberant field, which in a best case scenario will buy you 3dB (i.e a barely noticeable improvement). Short improving the isolation (i.e windows and exterior partition construction) there isn't anything you can do about the direct field.
A few strategically placed plants or sound dividers - think cubicle walls but far less intrusive - can also help.
Massive barriers can help in outdoor noise propagation scenarios. In this type of situation, the outdoor noise is impacting the exterior facade, causing it to vibrate, and is re-radiating sound in the interior of the OP's space. This means that the source of sound is a large area, not a point source. The sound is effectively coming from "everywhere", and so you don't get the same kind of path length difference attenuation from barriers like you do when you have a point source that is far from the receiver. This is exascerbated by the fact that the intrusion is low frequency which diffracts around corners far more than higher frequency sound.
Plants are not massive enough to be of any significant help. To put things into perspective, a dense forest that's 100m in depth will only attenuate sound 2-3dB, and that's mostly a high frequency reduction.
If you must go with a noise generator (which I don't recommend), try pink noise instead of white. The sounds from the street you try to mask out are going to be mostly low frequency, and white noise will mainly add more sound energy in the higher end of the spectrum.
White noise will add equal sound energy across the spectrum. Pink noise will add more energy in the lower frequencies. We don't typically recommend noise masking for low frequency intrusions into offices and other facilities we consult on because the masking is generally perceived to be more annoying than the original problem. It's best used when there is a speech privacy problem in large open offices because there isn't ENOUGH background noise.
Upgrading your window would typically be recommended, but will only do a little for low frequency. Note that in glazed assemblies, the framing is the weak point. STC 35 is where most frames will top out (even though the glazing will advertise higher STCs into the 50s). If you want a really solid window construction you need an isolated frame assembly which is two frames in series that do not touch each other and which are isolated from the surrounding structure using 3mm thick neoprene gaskets. Each frame supports a separate pane of glass. The inside perimeter should be lined with glass-fibre to prevent standing waves in the cavity.
Overall thickness of the glazing might be 2-3"
Re:And the motorcycles .... (Score:1, Informative)
It's precisely leaving all that baggage behind, focusing on going where you're going, that gets you that feeling of freedom. Not access to a dirt road you couldn't manage in your car.
You're generally alone and responsible for yourself. You're focused on going somewhere, because you have to be. You're not just trapped in a box between work and grocery, listening to the market report drone on in the background, trying to remember if you paid the cable bill.
Every nerve on your body is actively engaged. You feel the wind pulling on you, you feel road in the seat of your pants, your hands are telling you when the front wheel is tugging a little into a crack in the road, and your eyes are scanning. And yet you're probably pretty relaxed, because you know what you can do and what your ride will do, even if you don't know what's coming a half mile up.
And yeah, it might rain. You might stop somewhere you've never been, or you might tough it out. You'll worry about it when it comes to that. Either way, you're in that moment because you don't have a choice.
So yeah, we use, "freedom" as shorthand, but it's about doing something that you enjoy, without the burden of everything else weighing you down (physical or otherwise), because you couldn't afford to have it on board even if you wanted to.
Re:are the windows.. (Score:5, Informative)
Triple pane really doesn't do that much for sound deadening according to the Canadian Building Digest [google.com].
Tripple panes with dissimilar glass thickness works better,
But having a different type of glass on the inside works much better.
Typically they use laminated glass for the soundproufing inner pane, with glas laminated to plastic pane which dampens transmitted vibration.
There are commercial windows available [soundproofwindows.com] for this. These solutions seldom work where you intend to open the window to let in a breeze.
If you don't want to buy entirely new windows there are simple and less costly interior add-on panes [indowwindows.com]. This preserves the ability to open the window.
Re:And the motorcycles .... (Score:4, Informative)
I am a rider, and I have been through the MSF course, I recommend it.
No he is right, loud pipes most certainly do NOT save lives. Read some of the other comments, they are spot on. The majority of sound is heard right next to or behind the bike, not in front. Also, insulated cars and loud stereos, as you point out, can mostly cancel out bike noise.
Also... the noise is easily loud enough to damage hearing. In fact, motorcycle riders on the highway are advised to wear ear plugs, because even the sound of the wind will damage your ears over time in a full face helmet above 40-50 mph or so (never mind 80 mph :) ... thats loud)
What a motorcyclist has however is vision. A riders head rides almost as high as an SUV. He is also small. He has a lot of ability to avoid accidents, using his vision, size, and ability to accelerate.
I mean yes, there is a blind spot.... a good rider stays the fuck out of them and is very mindful of them when it can't be avoided. A good portion of being a good rider in traffic is assuming cars might not see you and riding specifically to increase visibility.
Good riders learn to use lane position to make sure they are seen and keep cars in their space, and make space for escapes. (sometimes you want to practically hug the lines)
Then... they practice evasive moves. A bike is a very agile device, but, if you don't intuitively know what to do, you will do the wrong thing. A lot of riders (a stunning number) don't even know that the bike counter-steers.
The vast majority of motorcycle accidents can be avoided by smart riding and avoiding the situations where a driver not seeing them means they die. That's never a smart bet. Assume they can't see you, make them see you.