overtone series

In acoustics, an overtone is a tone that sounds above the fundamental tone when a string or air column vibrates. When the entire medium vibrates, it produces the fundamental tone, also known as the first harmonic. If the medium vibrates in sections, it generates overtones, or harmonics. While the fundamental pitch is usually heard clearly, overtones can be perceived with concentration.1

Harmonics are a specific series of overtones where their frequencies are exact multiples of the fundamental frequency, creating simple frequency ratios like 2:1, 3:1, and 4:1.1

However, some musical instruments produce nonharmonic overtones, meaning the overtone frequencies are not multiples of the fundamental. The specific overtones favored by an instrument significantly influence its musical timbre, or tone color. For example, the "woody" sound of a clarinet is due to its emphasis on low-frequency odd harmonics, while the more nasal sound of an oboe results from the presence of all harmonics with a greater emphasis on higher frequencies.1