This being WRT resonating pipes. Apparently the acoustical length of the pipe is different to the physical length due to the vibration of the sound particles moving the particles at the opening so that the physical length is no longer the length of resonance. I've found many sources on the broad topic on end correction, and I know that it's commonly accepted that the end correction of a closed pipe is ~0.6*r, where r is the radius of the pipe. I've been doing some research, and I really can't understand why this is the case, however, no matter where I search, I can't find any sources on the topic. P.S any sources would be greatly welcomed!