Open tube

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In the field of acoustics, a tone is created by the periodic vibrations of air. There are several ways in music to create such vibrations. One of these is to use a tube and to blow across the end. This creates a note of a given frequency, depending on the length of the tube and the pressure of the air.

An open tube is a tube in which both ends are open. The tube resonates at a single fundamental frequency or note. An open tube resonates at the same frequency as a closed tube of half its length. In an open tube, an antinode always appears at each open end.

By overblowing an open tube, a note is obtained that is an octave above the fundamental note of the tube.

For example, if the fundamental note of an open pipe is c1, then overblowing the pipe gives c2, which is an octave above c1.