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An introduction to guitar harmonics

Harmonics on guitar are notes that are played by lightly touching the string as opposed to fretting it at a certain point on the guitar neck. Instead of creating a simple vibration sound, these give a chime-like quality that adds depth and flavour to playing and can also be used as pedal tones or drone notes. There are, however, many kinds of harmonics and understanding all of them, whilst not essential to guitar itself, greatly increases your melodic and tonal possibilities. So without further ado, let's have a look at what we can do:

Natural Harmonics

The most common form of harmonic and the easiest to do. To create a natural harmonic, you lightly touch the string at the desired fret, pluck the note and then swiftly pull your finger away to allow the note to chime. Technically speaking, natural harmonics can be performed anywhere on the guitar neck, but certain frets will have a clearer sound and a preferred intervalic quality relative to their open string:

12th fret - octave

7th/19th fret - octave + perfect 5th

5th/24th fret - second octave

4th/9th/16th fret - second octave + major 3rd

3.2 fret - second octave + perfect 5th

Songs to listen to: Yes - Roundabout

Tommy Emmanuel - Angelina

Touch Harmonics

Essentially the same concept as a natural harmonic, a touch harmonic is created by fretting a note and then creating a harmonic relative to that fret. Example - a 12th fret touch harmonic made whilst fretting the 2nd fret would be performed on the 14th fret. There are several ways to do this, but the most common is to use the index finger of the picking hand to rest above the fret and either the thumb or a plectrum held between the thumb and middle finger of the picking hand to chime the note. These are also known as 'classical harmonics'.

Songs to listen to: Eric Johnson - SRV

Pinched Harmonics

Particularly common in heavy metal. These are basically an extension of the touch harmonic concept. The actual harmonic itself is made by chiming the note with the plectrum and creating the harmonic with the picking hand thumb immediately afterwards. It's a difficult technique to master requiring a great deal of trial and error playing. To get the really high-pitched 'squeal' harmonics, you have to go past the 24th fret and look to the harmonics above the guitar body itself.

Songs to listen to: Just about anything with Zakk Wylde or Dimebag Darrel

Slap Harmoics

Another extension of the touch harmonic concept, this method is fairly self-explanatory. You basically slap the guitar with your index or middle finger at the desired harmonic node. The advantage of this style of harmonic is that it can be used to chime a whole chord at once.

Songs to listen to: Eric Johnson - Trademark

Harp Harmonics

My personal favourite. This really is just a concept that utilises both touch harmonics and normal fretted notes. The idea behind harp harmonics is to alternate between playing a touched harmonic and a fretted note so that the notes blend into each other and create a 'cascading' sort of sound. Tommy Emmanuel is particularly known for having mastered this technique.

Songs to listen to: Tommy Emmanuel - Somewhere Over the Rainbow

That just about covers it. Not all of these techniques are going to be essential to every guitarist of course, but if you undertake to getting at least some of them under your belt, you're going to be armed with a wider range of tonal qualities to experiment with. Look to people like Steve Vai and Joe Satriani for ideas on how to embellish simple ideas with harmonics with use of the whammy bar. Above all, experiment with these and just have fun!

By understanding a few basic physics principles, you can manipulate and exploit the natural resonant frequencies of your guitar and get some truly amazing sounds.

The Theory

Everything in nature has one or more resonant frequencies. These frequencies are a property of that object, and are determined by a number of factors, including density, size, shape, material, internal structure, etc. The reason this matters is that if you disturb an object with a force that has the same frequency as one of the object's resonant frequencies, the object starts going crazy. An famous example is hitting the E key on a piano and seeing the E string on a nearby guitar start to resonate. What happens is the sound waves moving through the air at a frequency for the note E hit the E string on the guitar. Well, a resonant frequency of that string is E (that's why it's called an E string). So you get a very efficient transfer of energy from the source (the piano key and then the resulting sound wave) to the object (the string).

This doesn't just apply to musical instruments, however. If you look at pictures of the aftermath of earthquakes in big cities, you can see completely destroyed buildings right next to buildings that look brand new. The reason this happens is because the resonant frequency of the destroyed building was very close to the frequency of vibrations produced by the earthquake. For that reason there was a very efficient transfer of energy between earthquake and building, and the building shakes and shakes until it tears itself apart. On the other hand, the surviving building has a resonant frequency very different from the earthquake. For this reason, the transfer of energy was very inefficient and the earthquake couldn't do that much to the building.

Well, that's all fine and good, but how does it help my guitar-playing skills?

Guitars, like many musical instruments, are designed to have lots and lots of natural resonant frequencies. This abundance of resonances means that you'll get a strong, clear sound no matter what note you play. The guitar can be split up into two sections: the body (main cavity + neck) and the strings. Each of these sections have natural frequencies that help make the guitar sound better. While you can't do much with the way the body of your guitar is set up, you can adjust the resonant frequencies of your strings. That's what tuning is. When you turn the tuning knobs, you're adjusting the tension in the string. When the tension goes up, the resonant frequency of the string goes up, giving the string a higher pitch. Conversely, when the tension goes down, the resonant frequency of the string goes down, giving the string a lower pitch.

What this means for you is that you add very complex harmonies to simple melodies without actually playing any of the harmonics. The simplest way to do this is to start with the guitar in standard tuning. Figure out a simple melody that you can play using only the top two strings. Once you've done this, tune the lower four strings of the guitar to various frequencies that "fit" the melody; i.e. they appear in the chord structure of the song. Make sure to choose both major-sounding pitches like thirds or fifths and less structured pitches as they fit into the chord structure. Play the melody slowly, giving plenty of time for each individual note to resonate. Make sure that you do not touch the other strings. As you play, the four lower strings will resonate and make chords that complement the melody. As you move into different sections of the melody, the "ghost chords" will change to match it. Try out a number of different configurations to see which one produces the sound you like best.

This is especially fun for people who know advanced music theory, since they will be able to create a number of different, interesting sounds based on the chord structures of a song. But anyone able to play a simple melody on a guitar should be able to get hours of fascinating and rewarding music out of this.

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