Good day, gentlemen! A friend of mine asked me a question - he is making a project regarding the influence of the cavity shape on the spectrum of acoustic waves produced after "blowing" into this pipe. You know, many national instruments are based on a principle of the usual pipe. Actually, the goal of the project is a creation of a software that will simulate any musical instrument... Well, starting up with a simple model, lets consider a tube - open from both ends. we blow in one end, and the tube produces certain sound. He states (he measured/analysed the spectrum) that the produced frequencies depend linearly on the length of the tube. e.i. actually, the waves only of such wave lengthes appear, that have nodes/peaks on the endpoints of the pipe. does it make any sense? can you just give a brief explanation on the phenomenon? i have my own ideas regarding this specific pipe case, but surely it's better to hear yours also ;) Thanks in advance!