Robin! After the thread "Hidden slot" another question has come to mind: We have learned that the mouthpiece end is the open end, and from the laws of standing waves in a tube this should mean that the wave pressure is low in a mouthpiece, since the wave pressure is low in an open end. (unless I´ve misunderstood, of course!). Some people, who usually know what they talk about, say otherwise, so my question is: * is wave pressure low as I expect in the mp end? * if not, then why not? The part of the mp that I´m thinking of is the part immidiately in front of the lips. The fact that the pressure will vary with the size of the cross-section is not what I´m after. Instead I´m just asking whether the mp follows the same laws as any open end would do regarding pressure maxima/minima.