Nashville number system

The Nashville Number System is a method of transcribing music by denoting the scale degree on which a chord is built. It was developed by Neal Matthews, Jr. in the late 1950s as a simplified system for The Jordanaires to use in the studio and further developed by Charlie McCoy. It resembles the Roman numeral and figured bass systems traditionally used to transcribe a chord progression since as early as the 1700s.

The Nashville Number System can be used by someone with only a rudimentary background in music theory. Improvisation structures can be explained using numbers and chord changes can be communicated mid-song by holding up the corresponding number of fingers. The system is flexible, and can be embellished to include more information (such as chord color or to denote a bass note in an inverted chord). The system makes it easy for bandleaders, record producer or lead vocalist to change the key of songs when recording in the studio or playing live, since the new key just has to be stated before the song is started. The rhythm section members can then use their knowledge of harmony to perform the song in a new key.

The Nashville Number System, (also referred to as NNS) is similar to (movable-do) Solfège, which uses "Do Re Mi Fa Sol La Ti" to represent the seven scale degrees of the Major scale. However the NNS instead uses numbers to represent each of the scale degrees. In the key of C, the numbers would correspond as follows: C=1, D=2, E=3, F=4, G=5, A=6, B=7. In the key of B♭, the numbers would be B♭=1, C=2, D=3, E♭=4, F=5, G=6, A=7. The key may be specified at the top of the chart, or given orally by the bandleader, record producer or lead singer. The numbers do not change when transposing the composition into another key. They are simply relative to the new root note. The only knowledge required is to know the major scale for the given key. Unless otherwise notated, all numbers represent major chords, and each chord should be played for one measure.

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