September 22, 2009

one big continuous clap

when you go to a u2 concert, and bono tries to get everyone to clap in unison, you end up thinking about acoustic properties of the stadium and sound deterioration as a function of distance and volume, right?

they begin to play "bloody sunday" and bono makes the whole "everyone clap like me" motions. as usual, most fans aren't really that coordinated, coupled with the confusion of seeing him clap at one rate, hearing him clap at another interval, and everyone else around you smelling like beer, it takes quite a bit of time for the group to settle into a groove.
while the relative chaos ensues, i begin to wonder if i can, similar to focusing on someone speak whispering sweet nothings at a loud bar, tune everything else out and zero-in on clapping patterns that aren't made intentionally. with enough tries, i can hear even subdivisions, but not much else.
by the time i try to hear triplets the clapping is now reaching me more or less in unison, with a little fuzziness before and after when i perceive the clap to occur, sort of like
f(x) = | sin(x) |

then i noticed that as my neighbors clapped louder my task became much much harder, which made me switch my alter my train of thought (and this is all during the intro of the song mind you, because rachel gave me a, "please tell me you've heard of this song your face looks so lost" kind of look)

i began wondering given the appropriate acoustics, how many people would you need to arrange so that if they all clapped once at the same time (perhaps on a global countdown or coordinated via electric shock or something) that i would be able to hear continuous, same-volume sound for n seconds.

things to think about:
  • what kind of volume deterioration are you going to get out of the clap or sound? ie what kind of rate do sounds lose volume as they travel in the air?
  • this is probably impacted by altitude (let's to go denver! think john elway vortex football)
  • how loud are the people in the back going to need to be, how soft are the people right next to me going to be?
  • do i need to pack people in to try to get a close to continuous function of clapping? or can i just sparsely arrange people?
  • does the formation of the clappers matter? straight line (doppler effect) or should they spiral out away from me?
  • will i need to account for sound waves interfering with each other?
  • should i be using a different sound like an "aaah" or "beeep" or an explosion?
  • am i going to need to have problems achieving the volume necessary at larger distances?
  • how do we convince that many people to participate in this study/event?

[edit: people at work began to tear this train of thought down claiming
  • the clap is too noisy to really be that good of a sample sound to try and repeat
  • you wouldn't really be able to get much continuous sound at gillette stadium (roughly only 1/5s given sufficiently loud clapping at the far ends)]
  • you'd need another U2 concert to test out my theory
further thoughts for achieving 1s of continuous sound:
  • you can obviously do the calculation using the speed of sound to determine that you'd need someone roughly 1100ft away. so that's a problem already
  • to be sufficiently loud that you're the same volume at 3 football fields away as the person standing next to me is going to be pretty tough
  • directional vs non-directional sound and volume over distance?
  • i think U2 won't do another concert here for a while

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