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.
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.
FIGURE 3
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