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MagLev Trains Annoyingly Loud
crem_d_genes writes "You might hear that whistle blowing from that train coming 'round the bend, but tapes of the sounds produced by magnetically levitated and normal trains produced a result that was something of a surprise: Most people rated maglev trains as more disturbing than standard intercity trains. It had been previously known that the two types were about equally loud, but this study analyzed people's reactions to them. Since the effects on the environment will be part of the feasibilty studies for future development, acoustical engineers will have some new challenges. Some participants in the study said the sound made them 'feel insecure, some found it startling, and disliked the occasional shrill sound the maglevs produced.' The researcher postulated that unfamiliarity with the noise might be part of the problem."
Videos of maglev trains, with sound. My apologies in advance to the host.
/.'ing commence!
Let the
Sapere Aude - Homer
You can hear them better because there's less vehicular traffic during the night. When a city is on the move during the day, all the cars effectively produce a blanket of white noise that reduces your perception of all the other sounds.
It's good to use your head, but not as a battering ram.
White noise. During the day you're probably being bombarded with noise from thousands of sources all at the same time. During the night, that white noise is likely nearly absent.
"There is much pleasure to be gained from useless knowledge." - Bertrand Russell.
We don't get the freigh train whistle in The Netherlands, that I'm aware of. So the first time a freight train passed by me here in the U.S., you bet it freaked me out.
Now... I'm used to it.
Remember how when trains were first introduced, cattle would freak out, and the farmers were pissed at the railroad companies ?
Nowadays, trains zip by cattle many times a day, and they don't even bother to look up anymore.
Yes - people would just have to get used to the sound.
Unfortunately, people are still afraid of change - even if it's just a change in the sound of a train.
To summarize, during the day the presence of "masking" sounds makes it more difficult to hear distant sounds. At night, fewer masking sounds are present.
The web in some high speed paper mills moves at 8000 fpm, or about 90 mph. It's a 400 inch wide piece of nylon webbing, on top of which a warm slurry of .5% paper is sprayed at high pressure. It goes over rollers and dewatering points, where the water is sucked out of it by vacuum. Some of the rollers are small, so they have higher RPMs. At the other end of the machine, there are huge heated drums spinning at a faster rate (to pull the paper out). All of this is accompanied by pump noise, air compression noise, and vibration. It is so loud that earplugs are mandatory, and your chest hurts from merely being in the plant.
But I know exactly what its doing, so its not "out of control".
I want to delete my account but Slashdot doesn't allow it.
the turbo trains of the late 1960s were jet-powered, and also annoyingly loud. Were canned for that same reason.
In your experience, and in everyone else's.
The Fletcher-Munson Effect describes equal loudness curves - our ears are signifigantly more sensitive to tones between 1-6 kHz, with a peak sensitivity at 4 kHz. However, as SPL increases, those curves flatten out - at 0 phons, a 100 Hz tone has to be 10,000 times more powerful than 1 kHz tone to sound comparable in level, but at 90 phons, they can be the exact same power level.
Hypothesis for why this is is that it came upon us during our evolution to enable us to hear baby/animal cries from far away. The physical reason is that it has to do with the resonation frequency of the inner ear cavity.
-T
There are some videos on the German Transrapid project here:
http://www.transrapid.de/de/medien/video.html
They're mostly commercials, but you can get an idea of how it sounds like (try the "Test Facility Emsland" video).
Three years ago, I went went on a guided tour to Papenburg/Germany and had the chance to experience the Maglev for about 20 minutes. First of all: don't believe what critics say. Try it yourself - if you get the chance to ;)
The Maglev is definitely NOT loud, nor does the sound make you feel uneasy (you could barely hear a train passing at 100mph, and a full-speed maglev was not at all annoying either!). Plus, there are no vibrations - a little different from conventional high-speed trains.
The top speed was 430kph (almost 270mph, on tracks initially developed for a maximum speed of 100mph - the tour guide claimed).
just my 2 cents
High pitch sounds are more painful to listen to, but they are easier to block than low pitch sounds which can travel thorugh the ground, especially at ground level where barriers can block noises. High pitch sound doesn't travel as far either. I would wager that being right next to the tracks would indeed be a painful experience, but half a block away I bet it isn't as bad and 2 blocks away is probably easily tolerable. I would bet that it has much less vibration which is a big problem for trains. Some steps they can take to mitigate noise:
1. Planting heavy shrubs near rail lines. Plantings can be designed to absorb specific sound spectrums.
2. Sound blocking berms or fences.
3. Double foundation walls with an air cavity between which don't allow sound transfer through the ground.
4. Larger setbacks from the noise source.
The frequency content of a sound has a lot to do with how comforting or annoying a sound is. Incredible ammounts of money have been spent on this in the auto industry alone. Studies are done on the sounds of a car door closing to find the sound that makes people feel the most secure when the door has closed. What they've found is that the sounds of car doors closing with more energy in the low end of the frequency spectrum makes people feel more secure in the sound of a door closing.
Now lets apply this to trains. Normal freight trains generally produce a lot of low frequency sounds. Generally around 300Hz and below. Now the maglev trains could be a lot quieter, but if they make higher frequency sounds, even at lower dB levels, the sound will seem a lot more annoying than freight trains.
I live in an apartment building that's fairly close to some railroad tracks. I haven't gotten used to it actually. I notice when a train is going by every time. I especially notice when they make LOUD SHRILL GRINDING NOISES. It's the most annoying noise I have ever heard. I have no idea what's making that noise, but how could a maglev be any worse? If my window is open it drowns out anything quiter than normal conversation. It is LOUD, and you would think there would be some kind of government regulation about the train tracks and a residential building being so close together.
I imagine it's even worse for the people in the apartment building that's between me and the tracks.
The maglev goes faster and when it does it pushes more air than a regular train.The power to move the train increases with the square of the velocity due to air friction. That power is what bystanders are hearing. I couldn't read the study but I'd be curious to see how people rated two trains moving at the same speed.
In any event, if maglev is ever going to prevail, noise is going to have to be dealt with. It can be done either by encasing the train in a tube to isolate the noise or better yet, encase the train in vacuum tube and then really crank up the speed since you're not shoving air out of the way. The inventors of superconducting maglev which uses repulsion instead of attraction like Transrapid figure that a train could go coast to coast in under an hour using the equivalent of about 20 gallons of gas. The cost of course is in building and evacuating a 2000 mile long tunnel.
That page incorrectly tries to load WMP for an MPG file. here is the link directly to the MPG file:
g
http://www.transrapid.de/real/mpeg/TR_TVE_en.mp
I make these: http://beatseqr.com
You know, if I'm a couple hundred miles away - I wouldn't hear it at all. ;-)
:-/
Seriously though, why don't they try using small speakers placed along the line of the train which project anti-soundwave patterns so the two cancel each other out. Like the devices now being put into people's homes? And for those inside as well.
Here's another site about quieting down buses et al.
Oh well. I looked and could not find the sound device (electronic) which matches incoming sounds and then creates the alternate sound wave which cancels out the incoming sound. I saw it in a recent electronic's magazine but I can't find that either right now. So I know it's out there but I do not remember where. Sorry folks!
Someone put a black hole in my pocket and now I'm broke.
The sound of an old huey is a teeth gritting "thwack thwack thwack", thanks to the forward rotor tip appriaching the sound barrier.
It's like having someone cracking a bullwhip continuously nearby. Not loud, but bloody annoying.
They're a lot more tolerable when they're not at cruise speed.