Slashdot Mirror


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."

13 of 251 comments (clear)

  1. Audio links by Whispers_in_the_dark · · Score: 5, Interesting

    Does anyone know of links to audio samples of a maglev? I've never heard one and some rudimentary googling didn't turn them up.

  2. Noise Qualities by toxic666 · · Score: 5, Interesting

    The quality of the noise source is as important as its intensity (i.e. decibels). Some noise patterns are just plain annoying. For instance, in noise studies, helicopters are considered more annoying and have lower acceptable decibel thresholds; the old Hueys are a prime example.

    1. Re:Noise Qualities by Simonetta · · Score: 4, Interesting

      For instance, in noise studies, helicopters are considered more annoying...

      Maybe it's a Pavlovian response. The sound of an old Huey is basically that of a machine either coming to kill you or coming to carry you off to be killed.

      The huge whirling blades are subliminal reinforcements of the motif of the 'grim reaper'.

    2. Re:Noise Qualities by JaredOfEuropa · · Score: 4, Interesting
      Some noise patterns are just plain annoying
      Quite right. My favorite example: a dripping faucet. This noise can be very faint; just on the edge of what you can still hear. But be honest: when you're lying in bed, as soon as you have identified the source of that faint, constant tapping, you just have to get up and turn off that faucet!

      In contrast, a running AC can make quite a bit of noise, but the sound is continuous and similar to white noise. Almost no-one has trouble falling asleep to the sound of an AC, in fact, if you are being kept awake by a dripping faucet or other noises, switch on the AC and its noise may drown out the rest, allowing you to sleep. (I know, not the most environmentally sound solution...)

      That's the problem with sound pollution laws: they only take sound levels into account.
      --
      If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
  3. Odd thing about trains... by Jin+Wicked · · Score: 4, Interesting

    Can anyone explain this to me about um... "traditional" train sound, because I've always wondered: Why are they so loud at night? I know trains run through the city here regularly, and I can't hear the train whistles where I live during the day, even though I know they still toot them, but at night I can here the trains that have got to be at least ten miles from here. Why is that?

    I would be curious if the sound of these kinds of trains carried in the same way. Normal train whistles aren't really unpleasant, but I wouldn't want to be listening to screeching noises from several miles away while I was trying to sleep. (The fact that I usually sleep during the day is irrelevant. =P)

    --
    My Webcomic: Asylum on 5th Street
    1. Re:Odd thing about trains... by dj245 · · Score: 4, Interesting
      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.

      White noise is a very good thing if you want to not hear certain sounds. In some doctor's offices they have little noisemakers that plug in and just make a little whirring noise. They serve absolutely no other purpose at all. They just obscure the conversations between the patients and the receptionists.

      I employ a similar technique to reduce the apparent noise I notice from the dorm hallway. I don't actually buy special noisemakers though, instead I have several computers and lots and lots of fans. It works fairly well to drown out talking, but it doesn't get rid of the booming bass from the neighbors.

      --
      Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
  4. I'd like to hear the sounds because ... by DikSeaCup · · Score: 5, Interesting
    Though they suggest unfamilliarity, one might wonder if it's more of a frequency/pitch or timbre issue.

    The sound of a regular train (been a while since I've heard one) is rythmic, higher pitch clicking. I would guess that the maglev might be more lower frequency. Also, one might wonder if there's a sound beyond the range of human awareness that might be contributing to the feeling that the maglevs are "louder" or more annoying.

    I dunno ... you tend to feel louder high pitched sounds in your ears, whereas the lower ones you might feel more in your body.

    The author of this post would like to point out that unlike other posts, this one was more stream of thought, and less composed than his previous ones. In other words, he's talking out of his ass.

    1. Re:I'd like to hear the sounds because ... by elwinc · · Score: 4, Interesting
      I'd like to hear them too. My guess is the more annoying sounds of maglevs have more high frequency components than traditional trains. there may be a fair amount of energy in very low freqency "thumps" coming from a traditional train. The maglev may be mostly hiss and whistles as the air streams over the body. Also, I'm guessing the maglev goes *much* faster than the wheeled train to make the same overall dbs of sound.

      In my experience, high frequencies (maybe 1000 to 4000 Hz) are more sonically salient than lows. Thats why sirens and car alarms put alot of energy in those bands.

      --
      --- Often in error; never in doubt!
  5. Seems feasible to me. by JessLeah · · Score: 4, Interesting

    "Conventional" trains make noises ranging from low rumbles (slower trains) to what resembles gigantic versions of the "fwooooooooosh" of a racecar passing you (Acela and other modern high-speed trains). But loud, high-pitched sounds coming from a piece of machinery (e.g. a train) could make people think the machine is out of control.

    High-pitched mechanical sounds carry a connotation of machinery operating "out of control", or running faster than it should. I'll put it this way. If you walked into, say, a widget factory, and heard the machines cranking away with a low rumble, wouldn't you feel more comfortable than if they were generating a constant high-pitched whining? In which scenario would you fear, deep down in your gut, that one of those machines is about to go haywire, break down, and shoot a cog in your general direction? This is regardless of the actual speed of the machinery. Low sounds are just less unnerving in this case. (Or so I feel...)

    Perhaps the sound of a maglev operating at 150mph would be more unnerving than that of an Acela train operating at 150mph since the nature of the maglev sounds would make it "sound like" it's more likely than the Acela to disrail (even though, as a maglev, it already is 'disrailed' in a sense ;) ) and crush the hapless onlooker...

  6. The sounds of silence? Oh, planes, trains, cars... by Mr.+Roadkill · · Score: 5, Interesting
    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."
    Given time, people can become comfortable with anything. Who woulda thunk that we could sleep through traffic noise, normal rail noise, low-flying jet aircraft etc?

    Where once upon a time new technologies were just introduced, we now run the risk of getting them bludgeoned to death by special-interest groups and environmental impact statements. There is no reason why in time maglev sounds should not become a familiar part of the soundscape, barely noticed if at all, and a realisation that people might be uncomfortable with something just because it is new may help us determine whether something really is damaging or if it's just a baseless case of NIMBY (as opposed to "it really is damaging, so get it the fuck away from me") when people oppose something new.

    (aplogies if this is incoherent... it's been three hours since my last coffee)

  7. Primate sound response by sjames · · Score: 5, Interesting

    I wonder if it's perhaps as simple as our built-in responses to shrill sounds.

    Primates tend to make more shrill prolonged sounds when in distress. We are likely hard wired to go on alert when we hear distressed sounds from another primate. That would explain uneasy feelings and rating the sound as more intrusive and objectionable than a rumble and clicking sound which would be fairly meaningless to the lower parts of the brain.

    It's a two fold problem that will likely call for psychologists and neurologists to determine what is so distressing and annoying about the sound, and then accoustic engineers to figure out how to alter the sound so that it no longer has that characteristic.

    Nothing more than a hypothesis here, but quite testable.

  8. Re:White noise generators? by gclef · · Score: 4, Interesting

    Those aren't actually cancelling the noise you're hearing, they're just masking it. Basically, it's not that it's quieter in your office, but the noise floor is higher, burying the annoying sounds in white noise.

    The same thing happens on airplanes. If you're ever flying somewhere, bring your walkman/mp3 player. Compare the volume you have it set to for normal use with what you have to crank it to when on the airplane. It's pretty disturbing how high the noise floor is on an airplane. (I wear earplugs on airplanes for just this reason.)

  9. the noise is likely caused by the chop frequency by gemtech · · Score: 4, Interesting

    (Pulse Width Modulation, PWM) of the power to the electromagnets. That frequency can be changed, within limits. I've been on mag-levs at Kings Island (Ohio) years ago, they are a bit annoying.

    --
    Insanity: doing the same thing over and over again and expecting different results. Albert Einstein