In a technical sense, music is a grouping of sounds that are constrained by the laws of physics. Harmonics make a great case study in how physics affect sounds.
On the guitar, harmonics—the result of the physics of string vibration—occur naturally at points called nodes along each open string and more prominently at a few specific frets. These are called natural harmonics. Most guitarists encounter this kind of harmonic first in their development, as a natural harmonic is easier to produce than its artificial cousin (more on this below). Before we begin, check out FIGURE 1 for a summary of the common natural harmonics and their locations across the fretboard.
FIGURE 1: OPEN HARMONICS
When a string is plucked and allowed to ring openly, the tone produced is called the fundamental. By lightly touching the sting at the 12th fret—directly above the fret wire—prior to striking it, you cause the string to vibrate in halves, producing what is called the 1st harmonic, a pitch that sounds one octave above each fundamental. The 1st harmonics for the guitar’s six open stings are depicted in FIGURE 2.
By touching the string at the 7th or 19th fret, the string vibrates in three sections, producing the 2nd harmonic [FIGURE 3], which sounds an octave plus a perfect 5th above the fundamental.
Touch the string at the 5th or 24th fret, and it vibrates in four sections, producing the 3rd harmonic [FIGURE 4], which sounds two octaves above the fundamental. (If your guitar doesn’t have 24 frets, you can generally find one of these harmonics over your neck pickup.) If you execute these harmonics properly, you’ll hear a series of round, bell-like toes.
Now that you can play these natural harmonics, let’s spice them up a bit.
First, FIGURE 5 shows a bouncy little 3/4 piece that intermingles natural harmonics with regular fretted notes above the open 5th string.
Taking it one step further, FIGURE 6 is built solely on natural harmonics. Such a melody would sound great in a rock context. This figure is a bit tricky, as it requires that you shift position quickly in order to hit the harmonics in rhythm, so start slowly and work your way up to tempo. Classic applications of natural harmonies are heard in the intro to Yes’ epic “Roundabout,” as well as throughout Jimi Hendrix’s legendary “Little Wing.”
In addition to natural harmonics, guitarists often use artificial harmonics, which occur on fretted notes. But the physics described earlier still apply. How?
Although fretting a note essentially changes the length of the string, the fretted note simply becomes the new fundamental—and so the node-point ratios remain the same. Therefore, the 1st harmonic is located 12 frets above the fretted note; the 2nd harmonic seven frets above; and the 3rd harmonic five frets above.
There are three types of artificial harmonics. The first is the tap harmonic, which is produced by tapping a string directly onto the fret wire with a pick-hand finger, either 12, seven or five frets away. Using a G major barre chord, let’s tap through some 1st harmonics [FIGURE 7A]. In the tab, the number to the left represents your fret-hand position; the number in parentheses indicates the fret onto which your pick-hand finger (preferably your index or middle finger) taps. FIGURE 7B ascends in 2nd harmonics and descends in 3rd harmonics.
Perhaps the most famous rock guitarist to routinely use tap harmonics is Eddie Van Halen (check out his intro on “Mean Streets”). FIGURE 8 contains a mean tap-harmonic riff inspired by Van Halen.
The second (and slightly less common) artificial harmonic is called a harp harmonic. In this technique, your pick hand’s index finger lightly touches a string directly over the fretwire (as in natural harmonics), while a different pick-hand finger (or thumb) or a pick is used to pluck the string.
As with tap harmonics, the same node-point ratios apply. The 1st harmonic is located 12 frets above the fretted note; the 2nd harmonic seven frets above; and the 3rd harmonic five frets above.
The difference, then, between tap and harp harmonics is that the latter has a clearer bell-like tone that is closer to that of a natural harmonic—and is more difficult to execute. Masters of this unorthodox technique include Chet Atkins, Lenny Breau, Eric Johnson and Russell Malone.
Using the G barre chord again, let’s play some harp harmonics. FIGURE 9 ascends the G chord using the 1st harmonic and descends on the 2nd harmonic. Once you’ve played those, try ascending and descending using the 3rd harmonic.
You can also play melodies using harp harmonics exclusively. This requires precise coordination of your fret and pick hands, as seen in FIGURE 10, an example derived from the G major scale.
One of the most effective (and most demanding) ways to use harp harmonics is to integrate them with fretted notes, thereby creating cascading sounds. In FIGURE 11, this approach is used to spruce up a C major pentatonic scale. Barre the 5th fret with your 1st finger and pluck the harmonics with either your pick-hand thumb or a pick, and the natural notes with your pick-hand middle finger. Work through this figure slowly, as it’s a tough nut to crack. But work hard, as that nut contains one of the guitar’s sweetest rewards.
The pinch harmonic is quite an attention-getter. When Zakk Wylde started playing with Ozzy Osbourne in the late Eighties, Osbourne told him that these squealing harmonics would one day become his calling card, and he was right.
Pinch harmonics are produced by simultaneously attacking the string with a pick (or fingernail) and lightly touching the string with the outside edge of the pick-hand thumb (near the nail). Remember the physics lesson? By brushing the string with the flesh of your thumb, you create a node point, causing the string to vibrate in multiple sections, thus sounding a harmonic, the pitch of which depends on the placement of your attack.
In FIGURE 12, some pinch harmonics—in this case squealing E, B and D notes—are played on the 5th string’s 7th-fret E, atop a pedaled open 6th string.