What Are Overtones in Music?

If you pluck the string of a guitar, a violin, or any stringed instrument, you may notice different sounds produced by the single note. That sound you are hearing as the sound vibrates through the air is called an overtone. But, what are overtones in music?

All vibrating bodies, especially instrument strings, have a natural set of overtones. We sometimes refer to them as harmonics.

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A Simple Definition

When you play a note, you create what is called the primary frequency or the fundamental. Any frequency that is greater than the fundamental or primary frequency that is simultaneously created is called an overtone.

In other words, overtones have a higher pitch that is produced by the fundamental or lowest note. The principal or primary sound you hear is what is known as the fundamental note. That is the prominent sound. But the overtones or harmonics will always be there.

The overtone then is a general description that refers to any standing wave with a higher frequency. As I said, they are often referred to as harmonics, and you may also hear them called resonances.

The Basic Frequency Plus A Greater Frequency

There are not specifically assigned frequencies that are known as overtones. They are any frequency that is greater than the fundamental frequency.

As I said, you will hear the fundamental or principal note. But you may not notice the overtones the vibrating string is creating. However, they are always there and are actual sounds that are produced along with the main note.

And what about your vibrating vocal cords? As instruments have overtones, so too does the human voice.

How Do They Form?

The overtone, or harmonic, is formed by the overlap that occurs between the two high points of their sound waves. To use an example, if you take any note, the octave above it will always be twice the note’s frequency.

That means the higher points of the lower note will experience overlap with the higher notes’ high points on every other occasion. Plucking a guitar string will mean you will hear overtones or other frequencies above the fundamental note. The fundamental note is the lowest frequency of that note.

So, Exactly What Are Overtones in Music?

I have used the term “the fundamental note.” But, there is activity around that fundamental note that is more than interesting.

Whatever note you are playing is called the fundamental note. That also applies incidentally to a note that is sung. If you are playing a D, then that will be the note that will be vibrating most powerfully in the upper octave. The next strongest vibration will be the note a fifth above. If your first note is D, then this will be an A. The third strongest sound will be an octave above our fifth. After that, the third will be heard.

The interesting thing I mentioned is that it constitutes a chord, usually a major chord. Made up of the fundamental note and its overtones or harmonics.

The Natural Way Of Things

This is not a clever trick; it is the way sounds are created. Overtones occur naturally; they are not, in the natural sense, created by musicians.

Sometimes, they can hardly be heard at all. Other times, they are clearly audible. However, whether you hear them or not, as I keep saying, they are always there.

Surprising At First

It can be quite a surprising experience at first when confronted with audible overtones. You may wonder where that extra sound is coming from. This applies especially to singing groups who perform without a music backing of any kind, which is known as “Singing A Cappella.”

Singers who perform in those situations have very good pitch by way of necessity. And while they are singing, they will often hear overtones that are being created above them. At times, it can sound like an extra singer.

Singers Will Need Good Pitch

It is not such a common occurrence with singers who haven’t got good pitch. They are not likely to pick up the sound of overtones.

There are two types of overtones, and I shall look at that a bit later. Before I do, let’s look at whether overtones can affect the overall sound.

How Do We Know It Is A Guitar?

I mean, other than by looking at it. If you close your eyes and someone plays the guitar, you know what it is. How? Every instrument has its own unique sound quality. We call it the timbre.

That is how our human hearing system identifies the difference between a guitar and a trumpet. Each has a unique sound.

What Is Timbre?

Timbre is the quality or definition of a sound. As such, it gives you the ability to distinguish or identify the sounds of different instruments. The overtones that a musical instrument emphasizes will determine its timbre.

A further consideration is that the intensity and amplitudes of overtones are not constant. It is the amplitude, or the volume, of each of the partial overtones that will characterize the sound. That is one of the key things that determine the timbre of the instrument.

To find out even more about Timbre, check out my in-depth look at What Is Timbre In Music?

The Relationship Of the Overtones

Put another way, the relationship of the overtones to each other will determine the flavor and tone of the sound we hear. That relationship has its center in the various amplitudes between the overtones.

It’s also worth just returning to what I said about intensity. We have seen that the amplitude or volume levels of the overtones can vary. Other variables exist as well.

Some overtones will experience a sound drop-off or, at the least, a level of sound decay over different periods. The effect of this will be an increase or decrease in the intensity of the overtone. And that applies to each note played or sung.

Different Effects for Different Styles

This variation in intensity can even cause a change of the timbre that will be reflected by your style of playing. The timbre may change from playing in a smooth legato fashion to a quick or staccato style. Instruments can sound very different when played in different styles.

Two Different Types Of Overtones

Harmonic Partial

In this type of overtone, the frequencies are partials that are exact whole number multiples of the fundamental. This includes the fundamental as this is actually one multiplied by itself (1 x 1 = 1).

Disharmonic Partial

The frequencies in the disharmonic partial are not ratios with whole numbers. This could be 1.26 or 2.30 or any such number that is not a whole number.

Simply put, a harmonic overtone might be considered as an integer multiple of the fundamental frequency. Whereas the disharmonic overtones are not multiples of the fundamental.

In most instruments, the overtones will deviate only slightly from their basic harmonic frequencies. Therefore, they can be thought of as harmonic frequencies because they are near enough to each other. This might mean that they are not exact whole number increments. But they are close enough.

An Extra Requirement

For any frequency to be considered harmonic, it has to fulfill two requirements.

It must be a frequency higher than the fundamental.
It must be a whole number multiple of the fundamental frequency.

Just To Remind Ourselves

We have seen that overtones are harmonics and are the extra notes produced when a fundamental note is played. The loudest sound that you will hear is the fundamental note or frequency.

It’s the most identifiable sound that you will hear and what you might be expecting. This sound has other sounds or notes around it that can also be heard. These sounds can be heard to a lesser or greater extent.

The Extra Notes

We have seen that the next sound you might hear is an octave over the fundamental note. That would then be followed by the perfect fifth. To continue, there would be two consecutive octaves over the fundamental.

There will be further harmonics produced, but these are in smaller intervals. That means as you carry on, they will get quieter until they are inaudible.

Different For Every Instrument

The reason why instruments sound different and have a different timbre is this mixture of the upper partials.

Practical Example of Overtones

The easiest way to listen to overtones is to give yourself a practical demonstration. Choose a string, possibly the third or ‘G’ string. Don’t fret it, just touch it (or even flick it) with a fingertip (the third finger produces the best result) about halfway along its length (exactly above the twelfth fret wire on a guitar). That will produce an overtone giving you the first octave.

Now, touch it again and this time, place your finger about one-third along the length of the string (this is directly above the seventh fret on the guitar). Remember not to fret; just touch (or flick) as you pluck the string gently. That will give you an octave and a fifth.

Do it on different lengths of the string, and you will get different harmonics or overtones. Can you see how this could be incorporated into your playing style to create some great sound images? Here are some materials that may help:

Want To Learn More About Music?

We can help. Take a look at our handy articles on What Is Homophonic Texture In Music, What Is Negative Harmony, What is Melody in Music, What is Strophic Form In Music, and What Is AABA Form In Music for more useful information.

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