Harmonics and partials. What's the difference? People tend to use these terms interchangeably but that is not completely correct . After reading this short article, you'll know the correct terms too.

If a guitar string (or any stringed instrument) is plucked open, that is referred to as the first partial. Let's say, in this example, it vibrates at 100 cycles per second (cps). Now let's say the string is plucked again but this time instead of being plucked open your finger is resting lightly above the 12th fret. The string is now essentially vibrating in two halves. This is known as the second partial or in this instance more properly called a harmonic.

Harmonics, technically, are only octaves of the fundamental, in this case the frequency of the open string. So in the previous example the string is now vibrating at 200 cps or twice as fast as the fundamental.

What if the string is then plucked so it is vibrating in 3 sections? This is called the third partial (not harmonic). To sound a third partial of an open string on a guitar you would place your finger lightly above the 7th fret. This note you are hearing is vibrating at 300 cps.
 
How about the fourth partial? To sound a fourth partial on the string you would place your finger lightly above the 5th fret. Once again we can call it a harmonic because it is an octave of the fundamental. It will be vibrating at 400 cps or four times as high as the original note.

The 5th partial is made to sound by placing your finger over the 9th fret.

How about a sixth partial? This would cause the string to vibrate in 6 sections making the note sound 6 times higher than the original or 600 cps. Notice that this is also twice as high as our third partial. You can sound this note by placing your finger lightly above the third fret.

Let's go for the 7th partial. Place your finger lightly on the string over the 3th fret as above but move your finger closer to the 2nd fret, pluck the string hard and listen to the 7th partial. On my own guitar I found it easier to sound the 7th partial close to my middle pickup (Strat).
 
The eighth partial, now properly called a harmonic is a bit difficult to sound. I was able to play this by placing my finger between the 2nd and 3rd fret or you can search for it somewhere between the middle and back pickup.

Incidentally, the technique of listening to partials and harmonics is used by most piano tuners to tune a given piano string in relation to other strings.

Another way to find partials and harmonics is to take a tape measure and measure the length of the string from the nut to the bridge. Get yourself a calculator and start doing the math as to where each will sound. While this method is not truly exacting(thanks to physics and overtones) it will get you close. A trick you can use to make harmonics and partials easier to sound is to crank up the distortion on your electric guitar amp and make sure you select the pickup closest to the bridge. Have fun experimenting with where you can find various partials... or should I say harmonics?

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