Why does a cello sound different from a trumpet? Why does a banjo sound different from a guitar? Why does the wind sound different from a white-water river? The answer involves a few things—pitch (high sounds vs low sounds), volume, rhythm… But the most characteristic difference is timbre.

Better known as tone quality or tone color, timbre (pronounced TAM-b.r) is the fundamental quality of sound. Timbre can be harsh, hollow, bright, dull… It’s how we distinguish strings from brass. It’s the difference between your voice and your friends voice— or even shattering glass and a crash cymbal.

If a cello and a trumpet both play the note C at identical volumes, they still sound very different. This is timbre. Experienced musicians can even hear the difference in timbre between two different violins because they differ in construction.

What causes timbre? To understand this we will discuss harmonics and the overtone series. Here’s where it gets weird…

Every pitch you play on an instrument is an illusion—within each pitch you always hear a series of higher, quieter pitches (even though you don’t realize it). This is called the overtone series.

The lowest string on a violin vibrates 196 times per second when bowed, or 196 Hz (hertz). Remarkably, it simultaneously vibrates in multiples of itself: 2x, 3x, 4x, 5x and so on. So in addition to 196 Hz, you also hear the higher frequencies of 392 Hz, 588 Hz, 784 Hz, 980 Hz… These are called harmonics (or overtones), and together they form the overtone series. When you bow the lowest note on a violin you hear all of these pitches at the same time!

This pattern holds true regardless of the note you play or the instrument you’re on. Nor is it limited to music. It’s a natural result of the laws of physics. Every sound has a fundamental frequency and an overtone series resonating above it. Most of the time the fundamental frequency is louder than the overtones—this is what our ear focuses on.

A flute emphasizes the fundamental frequency while the strength of harmonics taper off—giving it a pure sound. An oboe emphasizes many harmonics (especially the higher ones)—giving it a very bright sound. A clarinet emphasizes the fundamental and odd-numbered harmonics—giving it a hollow sound. A crash cymbal has so many harmonics that it sounds like noise. The relative strength of harmonics is what creates a unique timbre!

Timbre is intuitive to everyone but most people have never heard the word. It is just as important to music as melody, harmony or rhythm. Listening to timbre enriches your musical experience and revitalizes the sounds of the world. Enjoy!

Jack Gaffney is a local musician and piano teacher. He can be reached at JackGaffney.com.