Harmonic Overtones and Resonance

The charts below show a fundamental combined with out of phase even ordered harmonics. Out of phase means that while the fundamental begins with a rise in air pressure, the harmonics begin with a drop in air pressure. Each successive harmonic is lower in amplitude than the one below it in frequency. The 2^nd harmonic is 1/2 the amplitude of the fundamental. The 4^th harmonic is 1/4 amplitude, the 6^th harmonic is 1/6 amplitude ... and so forth up the scale.