back to article BONG! Lasers crack Big Ben frequency riddle BONG! No idea what to do with this info BONG!

Vibrations emitted by Britain’s most famous bell have been mapped for the first time by engineers from the University of Leicester. As everyone must know by now, Big Ben is housed at the top of Elizabeth Tower, London, and chimes faithfully every hour over the capital. Its deep bong can be heard whenever a giant 200kg hammer …

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  1. TURN ON TUNE IN DROP TABLES

    "Anyway, if you're still here, thanks for the ad and page view."

    always a pleasure.

    1. An nonymous Cowerd

      what ads?

      1. CrazyOldCatMan Silver badge

        what ads?

        Something that non-technical people see. Or so I'm told.

  2. PhilipN Silver badge

    Other uses?

    Can they point their kit at a rock band and give us the sonic picture in 3D?

    Actually I guess that's what my brain does already.

    1. Ugotta B. Kiddingme

      Re: Other uses?

      already done. Sort of...

      Discovery Channel show "Time Warp" which films things in ultra slow motion to see what happens did this with superstar drummer Mike Mangini. (currently of Dream Theater). Even HE was impressed at the magnitude of deflection.

    2. CrazyOldCatMan Silver badge

      Re: Other uses?

      Can they point their kit at a rock band and give us the sonic picture in 3D?

      Actually I guess that's what my brain does already.

      Likewise. And not just Hawkwind[1].I'd suggest that Yes' Siberian Khatru might be a good place to start. Along with Barbers Adagio - especially the voice-only Trinity College version[2].

      [1] To be honest, I never understood the attraction of Hawkwind. They were a competent band sure, but nothing revolutionary or different.

      [2] Also called Agneus Dei - has an incredible bit of harmony where a dissonant peak resolves into a beautiful harmony..

      1. Anonymous IV
        Facepalm

        Re: Other uses?

        Agnus dei, please - does nobody know Latin any more?

        1. jake Silver badge

          Re: Other uses?

          Well, they don't teach logic in high school anymore, so Latae sententiae ...

    3. LionelB

      Re: Other uses?

      Can they point their kit at a rock band and give us the sonic picture in 3D?

      There are well-known pharmaceuticals for doing that.

  3. frank ly Silver badge

    Bong! Bell Bothering Boffins Bash Big Ben

    I feel better now.

  4. Natalie Gritpants

    Puzzled why they went up the tower steps

    It's a laser so why not take the lift up a nearby skyscraper and point it through the window? Quieter too and there's posh coffee in the lobby.

    1. Charles 9 Silver badge

      Re: Puzzled why they went up the tower steps

      I may be wrong, but one, those windows are pretty small, probably too small to scan the bell as it's struck, and two, what tall enough accessible structures are there close enough to Big Ben for it to work?

      1. GrumpenKraut Silver badge
        Boffin

        Re: Puzzled why they went up the tower steps

        Also the relative movement (vibrations) between two buildings would deteriorate the results unacceptably.

        Btw. subways cause a lot of vibrations even in buildings that are quite far from the tracks. This I found out long ago when attempting to make holograms, it failed all night and suddenly worked in the few hours when the trains paused. All of this despite using a massive stone table that was vibrationally damped.

        1. Anonymous Coward
          Anonymous Coward

          Re: vibrationally damped

          "All of this despite using a massive stone table that was vibrationally damped."

          It's all about the base.

          Except when it isn't, when the inertia of the base combined with the characteristics of the vibration damping is insufficient to hide the applied excitation from the extraneous external effects, and the signal you wanted to observe is therefore dwarfed by the extraneous effects. OK in your case it wasn't so much a signal you wanted to observe as a movement you wanted not to happen, but the same principle applies.

          Hey, it's Friday. Have a great weekend.

      2. John Brown (no body) Silver badge

        Re: Puzzled why they went up the tower steps

        "what tall enough accessible structures are there close enough to Big Ben for it to work?"

        Pah! They've been bouncing lasers off reflectors on the moon since the 1970's. And IIRC measured moonquakes with them too.

        1. Charles 9 Silver badge

          Re: Puzzled why they went up the tower steps

          "Pah! They've been bouncing lasers off reflectors on the moon since the 1970's. And IIRC measured moonquakes with them too."

          But to what level of precision? I believe the precision needed with the Big Ben experiment was on the scale of sub-millimeters. Could they measure the deflection of the lunar surface during a moonquake to the micrometer?

    2. phuzz Silver badge
      Pint

      Re: Puzzled why they went up the tower steps

      "there's posh coffee in the lobby"

      Isn't there a subsided bar in Westminster Palace?

      1. Toni the terrible
        Pint

        Re: Puzzled why they went up the tower steps

        Yes there ia a subsidised bar in the Houses of Parliament, just not for plebs.

    3. CrazyOldCatMan Silver badge

      Re: Puzzled why they went up the tower steps

      nearby skyscraper and point it through the window?

      Light-scattering from the pollution introducing errors I would imagine. And less bragging rights - "sat in a nice comfy coffee shop and did the odd measurement remotely" sounds a lot less rufty-tufty than "labouriously carried hunderds of KG of equipment up hundreds of steps on our backs before doing lots of intricate measurements in a freezing cold and draughty bell tower".

  5. Anonymous Coward
    Anonymous Coward

    "...or something far more sinister?"

    It's a form of mind control for our lizard overlords to keep Londoners from discovering cold beer and gravy.

    I wear my tin foil hat in the pub with my whippet.

    1. jake Silver badge

      No need for tinfoil hats with Whippets about ...

    2. CrazyOldCatMan Silver badge

      Londoners from discovering cold beer and gravy

      Well - they have one of those - pie and mash shops (wiv loadsa gravy) have been a feature of life in London for a hundred years or so.

      Not so many around nowadays - what with modern conveniences like home cooking about.

  6. andy k O'Croydon
    Headmaster

    "Its deep bong can be heard whenever a giant 23 adult badger hammer bangs onto the side of the 17.8 skateboarding rhinoceros metal bell, which was cast in 1858."

    1. The First Dave

      Downvoted for not translating the date correctly...

      1. madick

        But there isn't a Reg standard for the origin of time, or even a Reg standard for measuring time intervals. (http://www.theregister.co.uk/Design/page/reg-standards-converter.html). If there were, it would be possible to express the frequencies of the bell in sensible units rather than boring old Hertz.

        Perhaps time should be measured in b@gg@rs, where 1 b@gg@r equals the time interval between pressing the 'send' button on an email and, on realising that you've sent to the wrong address, shouting "b@gg@r!"

    2. PNGuinn Silver badge
      Boffin

      Re badgers and rhinososasososheges

      We need some el Reg units of time, and we need them ... er ....

  7. daztech

    No spectrum analyser?

    Any reason why it wouldn't have been easier to just point a microphone at the bell and use a spectrum analyser to find the resonant frequencies?

    1. diodesign (Written by Reg staff) Silver badge

      Re: No spectrum analyser?

      Too easy.

      C.

    2. Anonymous Coward
      Anonymous Coward

      Re: No spectrum analyser?

      "and use a spectrum analyser to find the resonant frequencies?"

      At a guess.

      That would also register any resonances in the bell tower too. There would also be mixing in the air to give other frequency products.

      The laser map shows extra information about how different areas of the bell produce which frequencies and at what volume. Presumably any flaws in the casting would show up as localised distortions of the picture. That might actually be a practical use for the technique.

      1. psychonaut

        Re: No spectrum analyser?

        So they only wanted to measure the bell end of elizabeths tower?

      2. LionelB

        Re: No spectrum analyser?

        The laser map shows extra information about how different areas of the bell produce which frequencies and at what volume.

        Yes, indeed. The idea was to map out the different (simultaneous) vibration modes of the bell. Essentially a high-tech version of the famous Chladni experiment:

        https://www.youtube.com/watch?v=wvJAgrUBF4w

        (pouring sand on a bell doesn't work so well).

    3. jake Silver badge

      Re: No spectrum analyser?

      Not appealing.

      1. Neil Barnes Silver badge

        Re: No spectrum analyser?

        I kinda wanted to downvote you just for the badness of the pun, Jake, but I restrained myself and vibrated the other way.

        1. Anonymous Coward
          Anonymous Coward

          Re: No spectrum analyser?

          and vibrated the other way

          Odd choice of phrase, is that because "swinging the other way" means something else?

          :)

          1. CrazyOldCatMan Silver badge

            Re: No spectrum analyser?

            and vibrated the other way

            Odd choice of phrase, is that because "swinging the other way" means something else?

            Same thing only much, much more quickly.

            1. TRT Silver badge

              Re: No spectrum analyser?

              But is is higher pitched if you hit it at a node resonant with the cup handle?

    4. Necronomnomnomicon

      Re: No spectrum analyser?

      Presumably the laser doppler vibrometer is the thing they're really testing/improving or whatever, and the actual vibrating subject is just something that's been picked for maximum publicity, rather than something that could be done more easily.

      1. Joe Harrison Silver badge

        Re: No spectrum analyser?

        lizard1: "How can we get the MP mind-control surveillance laser into position without arousing suspicion?"

        lizard2: "gahh make up some shit about bell bongs"

    5. DavCrav Silver badge

      Re: No spectrum analyser?

      "Any reason why it wouldn't have been easier to just point a microphone at the bell and use a spectrum analyser to find the resonant frequencies?"

      Because you can't hear the shape of a drum. I mean this literally, the shape of a drum cannot be determined from the sound it makes. (It can in reasonable general circumstances, but anyway.) Knowing the resonance of the bell ring gives little information about how it is being produced.

      1. GrumpenKraut Silver badge
        Thumb Up

        Re: No spectrum analyser?

        > Because you can't hear the shape of a drum.

        There. I spot a mathematical commenter!

        For those puzzled: You Can't Always Hear the Shape of a Drum.

    6. John Smith 19 Gold badge

      "Any reason why it wouldn't have been easier to just point a microphone at the bell "

      Yes.

      That gives you the frequencies it emits.

      This gives you the exact points on the bell it emits from.

      This tech's useful for things like tanks and other pressure vessels. Hit the structure with a hammer and scan for weak spots on the shape.

      Even used to test the integrity of the vacuum in food tins.

      1. Dan Paul

        Re: "Any reason why it wouldn't have been easier to just point a microphone at the bell "

        They have already been doing exactly that with Accelerometers molded into hammers for many years.

        1. jake Silver badge

          Re: "Any reason why it wouldn't have been easier to just point a microphone at the bell "

          Accelerometers in hammers? New one on me ... Mind you, I have tuning forks in a few of mine (Stanley brand "Anti-vibe(R)", recommended. Try one, you'll be hooked.).

    7. Doctor Syntax Silver badge

      Re: No spectrum analyser?

      "Any reason why it wouldn't have been easier to just point a microphone at the bell and use a spectrum analyser to find the resonant frequencies?"

      It was a follow-up to a visual demonstration of vibrational modes of a flat plate. The plate itself was pretty dreadful sounding with a lot of non-harmonic modes so the obvious follow up was to look at the modes of something made to be euphonious. The spectrum analyser in itself wouldn't show the mechanical basis of the modes. Having said that, they whisked through the results PDQ.

  8. Anonymous Coward
    Anonymous Coward

    Researchers with frikkin lasers

    a-shootin at our beloved guvmint too.

    Now where did I put that keg of powder...

  9. brotherelf
    Paris Hilton

    Yes, but what about

    Garland of Flowers? Oh wait, wrong ¡BONG! even though the weekend is almost upon us…

    1. Francis Boyle Silver badge

      Hear, hear

      Wanders off muttering darkly about the Trade Descriptions Act.

  10. Michael H.F. Wilkinson Silver badge
    Coat

    Did they find any bats in the belfry?

    Sorry, I'll get me coat

    1. CrazyOldCatMan Silver badge

      Did they find any bats in the belfry?

      No - they were all busy in Parliament.

  11. jake Silver badge

    Is Great Paul next?

    I hear it bongs like the clappers!

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