Imagine this in your mind’s ear: You pick up a guitar and lay a finger on the low E string directly above the 12th fret, making contact but not depressing the string, deftly pluck it and...
Imagine this in your mind’s ear: You pick up a guitar and lay a finger on the low E string directly above the 12th fret, making contact but not depressing the string, deftly pluck it and immediately remove your finger to produce a bell-toned E natural harmonic, and then, while letting it ring, do the same thing using a raking action to pick the top three strings low-to-high (G, B, and E). Hear that? (Of course, you could actually play it, but the “mind’s ear” is a powerful thing.) It’s the E minor chord in natural harmonics that kicks off a classic prog-rock song.
Okay, so you’ve been there/done that. But if you haven’t dabbled in harmonics much beyond the “Roundabout” intro—maybe you’ve discovered they also exist at the 7th and 5th frets, used them to tune up, or perhaps elicited a few Buchanan/Gibbons-style squeals and squawks—you may have wondered what’s really going on here. In a word, physics.
GOOD VIBRATIONS
A plucked open string vibrates in a continuous loop between its two points of suspension—the nut and the bridge. Conventional fretting shortens the string length, hence raising the pitch in half-step increments as you travel up the fretboard. What many don’t realize is that when we play any note, open or fretted, we hear what is called a fundamental pitch, one whose tonal characteristics are shaped by its inherent harmonic overtones. The harmonic overtone series is omnipresent in nature and is contained in varying degrees (though not always audibly) in every sound we hear, both musical and otherwise. It’s called a “series” because its order of ascending intervals always follows the same sequence regardless of the fundamental. Why? It’s all about division.
DIVIDE & CONQUER
Simply put,