Harmonics & Overtones
Play a C on a piano and a C on a guitar: the pitch is the same, but the waveform and overtone balance differ. That difference is down to harmonics. Understanding harmonics explains timbre and helps you predict how synthesisers can reproduce or reshape a sound's frequency content.
The Fundamental
When a string vibrates, it doesn't just vibrate as a whole - it also vibrates in halves, thirds, quarters, and so on, all at the same time. The fundamental is the main vibration that determines the pitch you hear. The additional frequency components are overtones; their balance helps determine the sound's timbre.
A vibrating string produces the fundamental and many harmonics simultaneously.
The Harmonic Series
The harmonics of any note follow a fixed pattern - each one is a whole-number multiple of the fundamental frequency. If the fundamental is 100 Hz, the 2nd harmonic is 200 Hz, the 3rd is 300 Hz, and so on.
* The 7th harmonic is slightly flat compared to the equal-tempered scale.
Notice something interesting? The harmonic series naturally contains an octave, a fifth, and a major third. This is why these intervals sound so consonant - they're built into the physics of every vibrating object.
Timbre: The Colour of Sound
Timbre (pronounced "tam-ber") is the quality that makes a piano sound different from a guitar, even playing the same note at the same volume. It's determined by which harmonics are present and how loud each one is.
Flute
Almost pure fundamental with very few harmonics. Smooth, clear, simple. Close to a sine wave.
Clarinet
Strong odd harmonics (1st, 3rd, 5th), weak even harmonics. Hollow, woody quality. Similar harmonic pattern to a square wave.
Violin
Rich in both odd and even harmonics. Bright and complex. Similar to a sawtooth wave.
Piano
Complex mix of harmonics that change over time - bright attack that fades to a warmer sustain. No simple waveform equivalent - the harmonics are constantly evolving.
Why Harmonics Matter for Production
EQ & Filtering
When you boost or cut frequencies with EQ, you're adjusting the volume of specific harmonics. Cutting highs removes upper harmonics, making a sound darker.
Distortion & Saturation
Distortion adds new harmonics that weren't in the original sound. This is why a clean guitar and a distorted guitar sound so different - distortion generates overtones.
Synthesis
Additive synthesis builds sounds by layering individual harmonics. Subtractive synthesis starts with a harmonic-rich wave and filters away what you don't want.
Mixing
Understanding harmonics helps you hear why instruments clash - their harmonics overlap in the same frequency range, creating muddiness.
Production Tip
A bass note at 100 Hz doesn't just live at 100 Hz - its harmonics extend up to 200, 300, 400, 800 Hz and beyond. This is why you can "hear" bass even on small laptop speakers that can't reproduce low frequencies - your brain reconstructs the fundamental from the higher harmonics. It's also why adding subtle saturation to a bass can make it more audible on small speakers without increasing the actual low-end volume.
Try it
Build the overtone stack a layer at a time.
The octave, fifth, and higher partials are what make a note feel rich instead of plain.
Key takeaway
Overtones are the frequencies above the fundamental that contribute to an instrument's timbre. The same note sounds different on different instruments because their overtone frequencies and relative levels are different.
Next: how to remove frequencies and sculpt the sound you want - filters.
Explore different timbres
Starts generates parts across instruments with different harmonic characters.