I recently talked about harmonics as they relate to music (see what are harmonics in music). Essentially in frequency terms, harmonics are the fundamental frequency and every octave above that of a note. This is compared to overtones, which are all heard frequencies above the fundamental note when it’s played (see harmonics vs overtones). While some of this relates to harmonics on guitar, it’s a slightly different context, so let’s identify and define what are harmonics on guitar.
What Are Harmonics on Guitar
When you pluck a string on the guitar, you hear the fundamental and a lot of overtones which are part of that sound. You’re hearing the sound of the note, the string, the body of the guitar, etc.
The same is true if you fret a note on the guitar, meaning you apply pressure against the fret board just above (closer to the neck) one of the frets rather than plucking an open string.
To play a harmonic on guitar, rather than plucking an open or fretted string, you lightly apply pressure on the string, just making contact with your finger at a number of key locations.
Specifically, the 5th, 7th, and 12th (and 17th, 19th, and 24th) frets (placing finger above, meaning OVER top of the fret) will provide a typically higher pitched, full tone which is devoid of overtones, just a clean harmonic of the note.
You can hear a clear example of harmonics on guitar at the outro of Oasis’ “Stop Crying Your Heart Out” (time stamped to the right position):
Aside from the delay on top of the guitar, you can hear the clarity of the notes here (the 12th string harmonics on the G and B strings then the 7th on the D string, specifically).
You can apply a capo to your fret of choice to shift the harmonic locations up that many positions, as well.
Using Harmonics to Tune Your Guitar
Similar to how you can use a plucked (conventionally fretted) 5th fret on an in tune string as a reference note for the adjacent higher open string to tune it, you can also use harmonics to tune your guitar.
Once your low E string is in tune, you can lightly place your finger on the 5th fret of that string and gently pluck, subsequently removing your finger as you do it to hear that harmonic ring.
While that note is ringing, repeat the process on the 7th fret of the next string up, in this case the A string.
While the two notes are ringing together, adjust the tuning peg on the A string so that there’s no dissonance between the two notes.
If it’s out of tune, you’ll hear that A string’s pitch wavering up and down quickly. The closer it gets to being in tune with the E string’s harmonic sound, the slower that wavering will become until it disappears altogether once the note is perfectly in tune.
You can then repeat the process with your D and G strings, but note that because the G to B string transition are missing a half step, you need to just fret the 4th fret of the G and play the full note as you normally would match that to the open B. You can then repeat the harmonic tuning process from the B to highest E to ensure your guitar is in tune.
Of course this is all predicated on the fact that your lowest E string is in tune.
This is an easier way to tune your guitar because you’re not hearing any overtones with harmonics to muddy up the tone, it’s purely the isolated harmonic which makes matching pitches easier.
Aside from tuning, harmonics on guitar can make for a refreshing bit of ear candy when used effectively in the performance, so try working some in the next time you’re tracking guitar to add to the song.
