distance, time, pressure changes...freq Vs. Distance

[petemoore]

  An interesting page about the lengths of a soundwaves.
  http://arts.ucsc.edu/ems/music/tech_background/TE-01/soundWPF.html
  ...there's no 'wind' involved, the air really doesn't even move, the pressure waves 'push' through it, alot like ocean waves with little to no actual horizontal movement of the water.

[momo]

Thats why it might be good for the air valve tremolo to either have a labyrinth style baffles inside the tube, just like the Bose technology to increase bass....the idea being(and that applies to spkrs with port holes)that lower frequencies have longer wavelenghts, if you dont let the wave go thru at least one cycle, you wont get the full energy of that wave....that is why when you stand at the corner of a street and you get hit in your stumach with this powerful bass coming from a HipHop dude playing that music in his car.He does not feel the energy you are feeling at the corner of the street because he is only at the begining of the 12 foot soundwave!, so he gets the initial burst, which is maybe 1/4 of the total energy of this wave. You at the corner get hit full on at the end of the cycle of the wave....and then you wonder how this guy can handle this sound pressure, and the truth is well you are getting more than he is! in the low end.
By putting a labyrinth baffle, you force the wavelenghts to increase the travel distance and complete the cycle before going out, and so you increase the number of low frequencies that have a complete cycle therefore more volume.
When you add a port, the longer wave lenghts have a place to go, but you have to use a spkr designed for that.(these spkrs usually have more travel in the cone assembly).


http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/learning/waveguide_solution.jsp

Also, even though the pressure changes dont really create wind, the moving holes on the disc will though!,but it might be interesting, a bit like the whoosh you get from helicopter wings turning slow.
I dont think it would be enough wind to create mic popping, perhaps have a bevel on the holes to diffuse the pressure changes and smooth out the whoosh in the sound.

Oh and I just realized that if you want to make this contraption a bit smaller...you would have to use maybe a 4-5-6 inch spkr?, then porting would be good to extract the more bass possible from a 5 inch spkr.(the bose labyrinth system is the best way to increase low frequency content on small spkrs, these engineers have found a way to trick/bend the rules of physics!). I have no idea if this would be better than using a closed system with a bigger spkr.

By the way Pete, Im sure that all im saying rings bells in your head, Im just always writing in the spirit of having many people read this, so im not thinking that you dont know any of this!
Cheers