Greetings, didn't know where to post this. To which category it fits, if even any. Anyway, I'm studying sound production and am doing a work on resonating frequencies of a certain tube. Please bare in mind I'm not a physician or in the studies of physics, just a musician trying to understand resonance in acoustics. Please move thread if in wrong part of forum I've done a test on how to calculate the actual resonating frequency of a certain tube with OPEN ends. I'm using a brass tube of 200mm with a diameter of 0.7 cm. In the calculation I came to the conclution of 847 Hz, but the actual frequency that's resonating while hitting the tube is 1687 Hz. I hit the tube while holding approximately 25 % of the tube to hold it on a node. So I don't disturb the resonance. It's the same frequency that's heard when dropping the tube on the ground without holding it. So it shouldn't be that I'm manipulating the frequency response by holding it on 25%. The deviation from 843.5 is small but I think what I'm hearing is the second harmonic (first overtone) and not the fundamental. But why does not the fundamental resonate? In all literature I read it says that it should be the fundamental frequency that is heard. So the fundamental frequency should be 843.5, why am I then only hearing 1687 while making it resonate? f1 =843.5 =fundamental frequency = first harmonic f2 =1687 =first overtone = second harmonic f3 =2530.5 =second overtone = third harmonic and so forth. What I then began to think was that when hitting the tube the "first overtone" is the one that's heard it must be that, but I can not explain why. When the calculus tells me the fundamental is 843.5 and the literature says it's the frequency that should be heard. I'd be glad if someone has a answer for this.