This Demonstration shows how a modern tenor or B♭ trombone works. The player can move the slide into seven different positions, numbered 1 through 7. The longer the tube, the lower the vibrational frequency of the air column and hence the lower pitch of the note that is played. The fundamental modes of each position (called the pedal tones) are the following: 1 –> B♭, 2 –> A, 3 –> A♭ (G♯), 4 –> G, 5 –> G♭ (F♯), 6 –> F, 7 –> E. More frequently played are harmonics of the fundamental frequencies, which are produced by the player's vibrating lips (embouchure). The first harmonic is an octave above the fundamental, while the second harmonic is an octave and a fifth higher.