The depth of the note of a drum depends on the diameter of the drum head. This means that excellent, very low pitched drums are so large as to be unwieldy - think bass drums. The problem is that there is a preconception that drum heads need to be circles. Just because it has been that way for thousands of years does not mean it cannot change.

I propose that a very large diameter drum head be folded such that the diameter of the head remains the same, but the area of the frame is much reduced. Imagine the big round circular drum head. Now fold it like a taco. Fold more times - so when viewed sideways it looks like an accordion. The distance a wave must travel remains the same - and the drum pitch is just as low.

Now fold this crenellated head the other way, making a letter U. Fold more times. The whole thing is now quite small, but the head is still the same diameter.

This could then be mounted on a coiled tube, similar to that used for a french horn. The far end of the tube points away from the drummer, out into the audience. It can be worn over the shoulder, but sounds like the god of all tympani.

It would be good to illustrate this, if anyone with that power feels up to it and has a clue what I am trying to describe here.
-- bungston, Jun 13 2005

Only halfway there... http://www.t-mobile...eblog=1118689039741
[daseva, Jun 13 2005]

Like this? http://bz.pair.com/fun/drumhead.jpg
Kind of hard for me to visualize... [bristolz, Jun 14 2005]

(?) Removing the Stone http://www.freepate...4526168/4526168.pdf
I see some overlapping ideas on this patent, maybe. [mensmaximus, Jun 15 2005]

Quiet Tyres http://www.newscien...s?id=mg15220613.900
Minimal Volume from Tyres [csea, Nov 18 2005]

I have doubts about keeping the tension in all directions.

Would the (alternate direction) standing waves in the drum cancel the sound in the air?

Finally, It's an interesting thought: how to get bass sounds from small objects.
-- Ling, Jun 13 2005


The crenellated head is folded "the other way", meaning perpendicular to the previously created folds?

I'm having a way tough time figuring out how tension will be applied to this. As [Ling] points out, how will you keep tension in all directions? Speaking just of the first fold as that's as far as my brain can go: Tension perpendicular to the fold would make the thing try to look more like a Pringle than a taco wouldn't it?

Would not all of those folds alter how the sound waves propagate through the drum head itself? I imagine that property to be significant.

Of course, I expressed the same skepticism before hearing certain Bose products.
-- half, Jun 13 2005


This is similar to adding up the diameters of a bunch of four inch diameter speakers and saying they are the same as one twelve inch diameter speaker. They don't sound the same.
-- mensmaximus, Jun 13 2005


[half], my husband says, "If sound were sandpaper then Bose would be a grinding disk." I think he might be an audio snob.
-- bristolz, Jun 13 2005


I predict this shape to dampen resonance very quickly.
-- daseva, Jun 13 2005


[bz], I think you might be right. Other than that, I'm sure he's a swell guy. :)

I was referring specifically to the decent low end that the "Wave" products produce from a relatively small package...folded waveguide chambers and such.
-- half, Jun 13 2005


I checked around a bit, and found that low frequency drivers for loudspeakers need to displace a large volume of air. Either they can do that by using a large diameter, or by moving further.

Folding the drum, I think, might reduce the volume of air that is displaced, so the drum head would be minimal volume indeed.
-- Ling, Jun 13 2005


Wouldn't folding the drum create interference patterns? The emission of sound from one side of the drum will self-interfere (!?) with the sound wave due from the folded sections. I would also think that the folds themselves will have a distorting effect, perhaps similar to a Doppler. I don't know why this would be - I'm just guessing.
-- Jinbish, Jun 13 2005


A rare bun because it made me think of some way of improving the lithotrypsy process of imparting a sonic boom to a kidney stone in order to disintegrate it.
-- mensmaximus, Jun 13 2005


I haven't the slightest idea as how to draw this.
-- bristolz, Jun 13 2005


Don't know if it will wok or not, what with the tension and all, and don't understand well enough without that illustration, but bun for your original thought.
-- zeno, Jun 13 2005


I am not sure how a differently shaped drumhead would alter the sound. The idea that it might cancel out is interesting. One could do an experiment with a bendable frame and alter the shape as it was struck.

Thanks for the illustration [daseva].

As regards dampening sound, that is an interesting topologic problem. There is no reason the circle is the best for producing sounds. Perhaps there is a head conformation which would augment itself and be louder than a circle? A good problem for one of those topo-modelling supercomputers.
-- bungston, Jun 13 2005


You only need to do the accordion folding once. That is, you can't perform the double folding unless you have wires to guide the peak/trough formations within the circle.
-- daseva, Jun 13 2005


With normal skins, I agree that the tone would suffer. With something more evenly tense, there might be some interesting variations here.
-- daseva, Jun 14 2005


You *can't* fold a stretched drumskin and keep it under tension. You might be able to make a cymbal or other metallic drum-oid object and fold the heck out of it, but only because it's a rigid surface. Give it a try, you might get some interesting tones.

My drum, when struck dead center, sounds dead. When struck slightly off-center, it gives much better tone.

I saw some drums in the Barranca del Cobre that had beads on a string stretched across the drumhead. The rattling noise made the drums sound HUGE.
-- baconbrain, Jun 14 2005


/You *can't* fold a stretched drumskin and keep it under tension./ - Not sure why not. Imagine the round frame folded to form a taco shape. If you dipped it in soap, you could make a bubble which conformed to the frame, going around the bend. Why couldn't a drum head do the same thing? The drum head is not folded, it is curved.
-- bungston, Jun 14 2005


A soap bubble is the best way to look this, yes. If you fold the frame like a taco, the film will assume a shape somewhat like a crisp/potato chip. The center of the bubble will pull toward the furthest-away parts of the frame, it will not fold like a taco. If you took a flat wire loop, and dipped it in bubble solution, you'd get a flat film--you can put all the bends you want in the outside of the loop, but the center of the bubble will still seek for the minimum surface area. I can't describe this any better--get a wire coat hanger, make any kind of loop, dip it in soap, and look at it.

Really, you've got a good idea here, if only you'd switch to a solid object. I have two metal springs from railroad cars that have a marvelous tone when struck--fifteen feet of steel coiled into less than a foot.
-- baconbrain, Jun 14 2005


Um, do you like your drums tuned, bungston? apart the tension questions this raises, bun for the thinking behind it. Kinda like a curly octoban, yes?
-- Paradiddlellogram, Nov 16 2005


Thanks for the kind words, [PDG], except for the word "octoban" which I do not know. As the preceding discussion illustrates, my ability to convey shapes with language is limited.
-- bungston, Nov 16 2005


I would put in a link if I knew how. Go on tama.com and have a look at their "original percussion" in the products menu.
-- Paradiddlellogram, Nov 17 2005


Octoban: An autobahn consisting of eight lanes, also a zone in which octopi are prohibited.
-- normzone, Nov 17 2005


Tehe.
-- Paradiddlellogram, Nov 18 2005


{When I first saw this I thought it meant} lowered volume (sound pressure level) from a drum in order to make practicing less disruptive to neighbors, etc. To which end, see, [link] Quiet Tyres.

Now that I see it is about reducing 3 dimensional volume, I am reminded of the pipe organ my dad built in our living room. Some of the 16' pipes were folded to fit in an 8' ceiling height. Acoustically, they were still 16' long!

The same could be done for a drum, especially a long narrow one like a conga drum. A bit tougher for a bass drum. Perhaps the accordianing could be temporary, for storage or transport, while braces could reinforce once put in play.
-- csea, Nov 18 2005


I have made a bass drum out of a washtub basin, whose bottom has folds. But I dont believe it sounds larger than a flat bottom one. The fundamental note - whose frequency goes down as diameter goes up - of a serrated head and flat one would be nearly the same.

You could have a special effect drum idea here, but you aren't going to beat the laws of physics with these folds. The sound depends on tension and folds go away under tension. You're not going to pack a larger sound into the back seat of a Civic by folding a drum, but you may get an 'interesting sound'
-- DeanRadcliffe, Mar 20 2009



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