3rd Bridge - Physical Explanation and Examples

Physical Explanation and Examples

On a standard guitar, the string is held above the soundboard by two nodes: the "nut" (near the headstock) and the "bridge" (near the player's right hand on a standard guitar). A player sounding a note on a standard guitar vibrates a single portion of the string (between the nut and the bridge, or between their fretting finger and the bridge).

In contrast, a third bridge divides the string into two pieces. When played at one part of a string, the opposed part can resonate in a subharmonic of the struck part, depending on a predictable mathematical ratio of the strings' lengths. On harmonic positions the created multiphonic tone is consonant and increases in volume and sustain because of the reciprocal string resonance. The sound is comparable with the sound of bells of clocks.

In the 1930s, Harry Partch experimented with this technique on an instrument he called a Kitara that had movable glass rods. In the late 1960s, Keith Rowe made occasional use of third bridge guitars, inspiring a slew of experimental guitarists (notably Fred Frith to use prepared guitars, inspired by John Cage's technique of the prepared piano. Classical guitar duo Elgart & Yates wrote a small book Prepared Guitar Techniques in which the technique is described and used in the added written musical piece, although not defined with the term 'third bridge' yet. From the 1970s, Hans Reichel's self-made and modified acoustic guitars sometimes featured third bridges.

From the late 1970s, Glenn Branca adopted Partch's theory and used amplified string tables for some of his symphonies. After being trained in the Branca orchestra, Sonic Youth applied their own guitars with screwdrivers, mainly in their early years. On their debut EP and the album Confusion is Sex this technique is often used. Afterwards Bradford Reed developed the Pencilina. Reed plays mainly with drumsticks hitting the strings as well.