Understanding Harmonics and Overtones

Last Updated:

In the world of sound design, studying harmonics is a key skill that sets beginners apart from experts.

Harmonics are the various frequencies that are within the main “tone” of any sound. Each of these frequencies is like an individual thread of sound that come together to form a larger piece of sonic cloth.

Understanding how these frequencies work together allows sound designers to shape audio with accuracy and a clear goal.

This guide aims to explain harmonics and how they’re used in sound design. By the end, you’ll gain a deeper understanding of how they affect the sounds we make.

Fundamental Tones Explained

The fundamental tone – the “heartbeat,” or main tone of a sound wave – is the lowest (most base) frequency in a sound’s harmonic series (the set of frequencies a sound is made up of). This basic, fundamental tone helps us identify the sound’s primary perceived pitch, acting as it’s tonal center.

It’s also the anchor for other frequencies within a sound called harmonics or overtones.

The fundamental frequency is typically the most dominant tone that is perceived when listening to a sound or musical note.

In complex sounds with many different frequencies, however, identifying the fundamental tone can be quite challenging.

The most dominant frequency is not always the lowest, but it is typically the one perceived as the pitch of the sound.

Here are steps to determine a sound’s fundamental tone, if you’re interested:

  1. Use a tool or instrument: You’ll need a tool or instrument capable of analyzing sound frequencies, like a spectrum analyzer or frequency analyzer software.
  2. Record or input the sound: Next, you’ll need to record or input the sound you want to analyze into your chosen tool.
  3. Analyze the sound: Once the sound is inputted, use your tool to analyze it. The tool will generate a frequency spectrum that shows the different frequencies present in the sound.
  4. Identify the lowest frequency: The lowest frequency present in the sound is typically the fundamental tone. This is because the fundamental tone is usually the strongest frequency and the one from which all other harmonics derive.

Harmonic Resonance

The fundamental tone also helps make the sound complex and rich by interacting with the physical aspects of an instrument, causing something called harmonic resonance.

Harmonic resonance refers to the phenomenon that occurs when an object naturally vibrates at certain frequencies. These frequencies, known as the object’s resonant frequencies, are determined by the object’s physical properties (ex/ shape, material, etc.).

In music, harmonic resonance is often used to enhance the sound of musical instruments. For example, the body of a guitar is designed to resonate at certain frequencies, which amplifies the sound produced by the strings.

In sound design, harmonic resonance is used to create specific sounds or effects. For example, a sound designer might use a resonant filter to emphasize specific frequencies in a sound, creating a resonant or “ringing” effect.

Going Deeper on Harmonics and Overtones

Harmonics in sound design refer to the frequencies that occur above the fundamental frequency of a sound. They are integral to the unique tonal quality of a sound and are multiples of the fundamental frequency.

Each of these frequencies contributes to the overall timbre of the sound.

In musical terms, harmonics are often referred to as “overtones” and are key to differentiating one musical instrument from another. For instance, a flute and a violin playing the same note will sound different due to their unique harmonic structures.

Harmonics and overtones are controlled in several ways during the sound design process – filtering, adding effects, shaping waves, etc.

Harmonic Resonance

The fundamental tone interacts with the physical aspects of an instrument, causing something called harmonic resonance.

Harmonic resonance refers to the phenomenon that occurs when an object naturally vibrates at certain frequencies. These frequencies, known as the object’s resonant frequencies, are determined by the object’s physical properties (ex/ shape, material, etc.).

In music, harmonic resonance is often used to enhance the sound of musical instruments. For example, the body of a guitar is designed to resonate at certain frequencies, which amplifies the sound produced by the strings.

In sound design, harmonic resonance is used to create specific sounds or effects. For example, a sound designer might use a resonant filter to emphasize specific frequencies in a sound, creating a resonant or “ringing” effect.

Multiples of the Fundamental

These harmonics, or additional frequencies, are called second, third and higher-order harmonics. They are integer multiples of the fundamental. That just means they’re the fundamental tone times two, three, and so on.

Sound is made interesting by the layers of harmonics and overtones that add to its fundamental tone.

Every overtone changes how we hear the sound’s feel and color. By emphasizing and de-emphasizing certain harmonics and overtones, we can create the signature sound of specific instruments, or something entirely unheard before.

The Harmonic Series

There’s a thing called the harmonic series in music. It’s a set of tones related to a fundamental tone.

It is expressed as:

1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 + …

In waveform terms it looks like this:

The Harmonic Series

A sound is balanced when its harmonics work well with its basic frequency. This balance is important for making a sound that is pleasant to hear and fits well in a piece of music.

The link between harmonics and musical intervals is important because it forms the basis of Western music theory. That means thinking carefully about the musical intervals between the basic frequency and its overtones.

Each harmonic naturally appears at certain intervals above the basic tone, creating a set of pitches that we see as fitting together. This is important for building chords and melodies.

Partials in Sound Design

If harmonics and overtones are the multiples of the frequencies that make up a sound, partials refer to any of the individual sine waves of which a sound is composed.

In other words, partials are all the individual frequencies that make up a sound, including the fundamental frequency and all the harmonics.

The role of partials in sound design lies in their ability to generate a wide range of sounds and textures. In sound design, partials act as the foundational elements that bring complexity to the timbre, providing a spectrum for creating nuanced sonic hues.

That means partials can be harmonic or inharmonic.

Harmonic partials are integer (whole number) multiples of the fundamental frequency, contributing to the perceived pitch of a sound.

Inharmonic partials are non-integer multiples of the fundamental frequency, often contributing to the timbre or tone color of a sound. These are often found in percussion instruments.

Why Partials Matter

Synthesis techniques such as frequency modulation (or FM synthesis) depend greatly on the comprehension and usage of partials. By changing the frequency of one waveform with another, you introduce new partials into a sound, significantly modifying its timbre.

You can both enhance the harmonic content of a sound and also create inharmonic frequencies, adding to the distinctiveness of the sound.

Harmonic blending is the act of thoughtfully merging partials at different levels to create a specific tonal quality or simulate real acoustic occurrences (i.e. live instruments).

The skill of merging harmonics and inharmonics is key to maintaining the perfect balance between musicality and complexity. To handle sound effectively through partials, you need a deep knowledge of how different frequencies play together in a sound wave.

Timbre and Harmonic Content

Timbre is a unique feature of every musical instrument and voice that allows us to differentiate sounds. It mainly comes from the special mix and balance of harmonics in a sound.

Timbral qualities are what let us tell the difference between a violin and a flute, for example, even if they’re playing the same note at the same volume.

A musical note’s character is more than just its pitch and volume.

Harmonic balance is very important because it controls how complicated a sound seems to our ears.

A well-balanced sound can feel full of life and very rich. But if some harmonics are too loud, the sound can seem weak or harsh. So, musicians and sound designers work hard to get the balance just right.

This helps to shape the sound’s timbral qualities.

So, a sound’s complexity doesn’t come from just one thing. It comes from many different harmonics, each adding its own color to the overall sound.

In sound design, adjusting timbre is both an art and a science. Whether it’s the warm sound of a cello or the sharp sound of a synth, the balance of harmonics is what unlocks all the different aspects of a sound’s complexity and timbral qualities.

Harmonics and Nature – Beyond Sound Design

Harmonics are everywhere in nature. They can be seen in everything from the way a canyon echoes to the songs of birds. They work on the principle of harmonic resonance.

This means that things, both living and non-living, vibrate when specific frequencies are hit, making some sounds stronger than others. This is key to how we hear our world.

We see the harmonic series in how nature is built. The complexity of the harmonic series adds to the beauty and depth of natural sounds. It could be the sound of leaves rustling or a river flowing. The way harmonics balance in these sounds is what gives them their unique sound.

Balance in harmonics is also important in the sounds of animals. The sounds made by birds and mammals show a great use of harmonics. The balance between the basic tone and its harmonics can communicate different things or even show the health of the animal.

Nature is filled with complex harmonics. Each sound interacts with others to create a mix that is both useful and beautiful.

The study of these natural sounds is more than just observing. It influences the work of sound designers. These professionals are inspired by how nature uses harmonics.

They try to copy its balance and complexity in their work. This makes the line between the natural music of the wild and the human-made music unclear.