13. The Twelve-String Guitar
The twelve-string is just that a guitar with twelve strings! In actual fact, they are not really twelve separate strings, but rather six pairs or courses.
The origins of the instrument are a little uncertain, though its definitely an American creation like the steel-strung guitar itself. Its likely that the influence came from either Italian or Mexican luthiers in the melting pot of New York, whose traditions included many double-course instruments such as the mandolin (Italy), and also the tiple (Mexico).
Most double-course instruments have courses strung either in unison (both strings at the same pitch) or in octaves. The lower courses of the twelve-string are strung in octaves a thinner string is added an octave above the standard guitar string, while the upper courses are generally strung in unison. The G course can belong to either group, but more often the former. The string spacing within each course is less than between courses, so each course is usually played as if it were a single string. This produces a noticeable difference between the sounds of upstrokes and downstrokes on the lower courses downstrokes accentuate the higher octave.
The twelve-strings distinctive sound is a little like a chorus effect, and is a product of the very different timbres within each pair as well as inevitable small tuning differences. Few players today play twelve-string exclusively, unlike historic figures such as Leadbelly and Blind Willie McTell, but instead use the instrument for specific songs where its sound is deemed appropriate. Strumming produces a big, powerful sound, and arpeggiated chords can be even more effective. The twelve-string is little-used for lead work as the pressure required to fret two strings at once tends to reduce fluency, and string bending and vibrato are more or less impossible.