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Girderphonic

 a ten storey building containing a single hanging girder
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In a ten storey building a single metal girder freely hangs, which extends into a space below the ground floor. In this underground space, the girder is surrounded by water, the level of which can be quickly altered by rapid action hydraulics. These hydraulics are controlled by a piano style reduced keyboard contained in a separate room. You may have figured out by now that this is the descriptor for a new analogue sound instrument.

Here's how it works: one person equipped with ear defenders delivers a single hammer blow to the girder, causing it to emit a massive vibration. This vibration is then attenuated by the rising and falling on the water, as the second operator controls the sound using the previously described keyboard. A row of identical towers would enable orchestrated sounds to be generated.

I have no idea if this would actually 'work', but that's why it's resting here in the halfbakery, as the construction crew lean on their shovels.

—xenzag, Feb 28 2016

Stomp Out Loud https://www.youtube...watch?v=fN5T8y8bCJ4
I dunno about girders, but it works quite well with what appear to be scaff poles. (~18 minutes in.) [Wrongfellow, Mar 04 2016]

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       sp. "acoustic"
—FlyingToaster, Feb 28 2016
   

       The pumps would be noisy. Would it be better to have rubber attenuators?
—pocmloc, Feb 28 2016
   

       The pumps would be soundproofed.
—xenzag, Feb 28 2016
   

       I don't think the water is going to do what you want it to do. At best, it is going to partially damp* the sound (acting at one end of the girder), and change the resonant frequency only a little.   

       (*Although this may appear to be a pun, it is, in actual fact, not.)
—MaxwellBuchanan, Feb 28 2016
   

       The water sloshing in and out of the pumps is what will be noisy, not the mechanical action of said pumpacious devices.
—pocmloc, Feb 28 2016
   

       Max - a small change will suffice. Perhaps some method of rapidly varying the viscosity would be good, but not easily achieved except in a one way, non reversible direction ie thixotropic substances?
—xenzag, Feb 28 2016
   

       But again, you will only be damping the vibrations - their pitch will not change as much. So, you may get some pitch variation, but the higher notes will be duller.   

       This might work if, instead of a liquid, you used a semi-solid and raised or lowered the girder into it. I think a few hundred tons of foie gras would have the right sort of consistency,
—MaxwellBuchanan, Feb 28 2016
   

       Liquefied carnivores it is then. They can keep their clothes on as they pushed and prodded along the sterile corridor towards the Soylent Green blender! ha
—xenzag, Feb 28 2016
   

       I'm a vegetarian, but I eat meat as well. No point being faddy, I always think.
—MaxwellBuchanan, Feb 28 2016
   

       An excellent find [Wrongfellow] though obviously on a much smaller scale and a reversal of the idea that it's the water level that changes, but it does prove that the idea would work. I would love to build it. More failed grant applications on the way then!
—xenzag, Mar 04 2016
   

       Of course, one major difference between a girder and a pole is the presence of a resonant column of air in the interior of a pole.   

       //a few hundred tons of foie gras//   

       Using mercury instead might enhance the desired "impedance mismatch" effect while also showing less undesirable damping.   

       Unfortunately, combining foie gras with mercury is far beyond my meagre culinary skills.
—Wrongfellow, Mar 04 2016
   

       I love the proposal to work around cumbersome, fussy pumps by varying fluid viscosity. And the idea of changing the water level rather than raising and lowering the girder. Tom Sawyer would approve!   

       But Max thinks the water will not work. I think it might. It is easy to take a pencil, or a butter knife, pr preferably 2 butter knives and tap while changing the free length - the pitch changes. Would water dampen as well as fingers?
—bungston, Mar 05 2016
   

       I can very much imagine the girder as sculpture, hanging in the open lobby of a skyscraper. The Chime of Damocles. But implementing this whole idea would get people wet. Plus the water would gush out into the street when people opened the doors. How to change the pitch of a hanging piece of metal?
—bungston, Mar 05 2016
   

       // Would water dampen as well as fingers? //   

       Water dampens a lot better than fingers, unless the fingers are bleeding or have been dampened themselves. Now, does water *damp* as well as fingers? That I don't know.
—notexactly, Mar 05 2016
   
      
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