Originally Posted by soho54
He never said a pipe opened at both ends.
The link discusses open and closed end cylinders. FWIW, a clarinet is a closed end pipe.
It helps to actually follow the link and read.....
"Let's send a pulse of air down a cylindrical pipe open at both ends (such as a flute, shakuhachi etc). It reaches the end of the tube and its momentum carries it out into the open air, where it spreads out in all directions. Now, because it spreads out in all directions its pressure falls very quickly to nearly atmospheric pressure (the air outside is at atmospheric pressure). However, it still has the momentum to travel away from the end of the pipe. Consequently, it creates a little suction: the air following behind it in the tube is sucked out (a little like the air that is sucked behind a speeding truck).
Now a suction at the end of the tube draws air from further up the tube, and that in turn draws air from further up the tube and so on. So the result is that a pulse of high pressure air travelling down the tube is reflected as a pulse of low pressure air travelling up the tube. We say that the pressure wave has been reflected at the open end, with a change in phase of 180°. In the open-open pipe, there is such a reflection at both ends."
Which is quoted from here:http://www.phys.unsw.edu.au/jw/flutes.v.clarinets.html
- and contains the quote Dennis posted. Again, reading first can be a good thing....
Transmission line or vented loudspeakers are not the equivalent of Helmholtz resonators, pipe organs, reed pipe organs, or reed instruments. Unlike a vented loudspeaker, the other devices require essentially constant radial flow of air across an orifice or open end to induce the pressure pulses that result in resonance. These conditions are not present in a loudspeaker to any appreciable degree. This sorry ground has been tread on repeatedly elsewhere and it is sad that people continue to cling to such wild extrapolations as if they possessed meaning or value for those deeply involved in loudspeaker design.