In the late ’50s, Neil Matthews, a member of the Jordanaires, (Elvis’ backup singers) devised a musical number system for the vocalists to use in the studio so they wouldn’t have to remember volumes of material. In the ’60s, studio musician and country artist Charlie McCoy adapted Matthews’ number system for writing chord for rhythm sections. (Charlie has played on dozens of hit records by Elvis Presley, Simon & Garfunkel, Johnny Cash, Bob Dylan, Roy Orbison, and many more.) Eventually, other studio musicians adopted it until it grew into a complete method for writing chord charts and melodies, known as the Nashville Number System. A chart using the Nashville Number System can be played in any key – no transposition or rewriting of charts is necessary. Regardless of key, the numbers maintain their same relationship with the song’s chord changes. Charts using this system employ rhythmic and dynamic markings, as well as chord voicing symbols, resulting in formal music combined with Nashville shorthand.
Chords can be written using either Roman or Arabic numerals. Most musicians using the system tend to write in Arabic numerals. At its most basic level, the system works thusly: a number is assigned to each scale degree, and each number is assumed to be a major chord unless other qualities are stipulated. For example, a triad normally built on scale degree 2 in the key of C would be D minor (D-F-A), but with the NNS, the “2 chord” is played as D major. To determine the duration of a chord, parentheses are used as measures. A chart in 4/4 time containing (1,2) (4) (5,4,2m) (1/3 4,5,1) would be read in the key of C as: Measure one: C major 2 beats, D major 2 beats. Measure two: F major for four beats. Measure three: G major one beat, F major one beat, and D minor two beats. Measure four: (here’s where it gets interesting) C major with E in the bass (1-chord over 3-chord), F major, G major, and C major, one beat each. To play the same song in the key of E, all you need remember is the E scale (E, F#, G#, A, B, C#, D#, E). Looking at the number chart, the song becomes much easier to play in the new key without having to determine intervallic relationships and scale degree qualities in your head at the speed of song.