Tuesday 30 January 2024

Roman Numeral Notation

Most music is written in one of the twelve major scales, and the Major scale has a pragmatically-central position in a (western) musician's technique.

Because all twelve major scales have the same intervals, anything we say about the musical properties of one scale will apply to any of the others. The Roman Numeral notation lets us do this: it abstracts out the tonic note, but fixes the Major scale.

I (tonic, first) the note that names the key
♯I / ♭II (sharp first, flat second) 
II (second)
 ♯I / ♭III (sharp second / flat third) 
III (third) 
♯III / ♭IV (sharp third / flat fourth) 
IV (fourth) 
V (fifth) 
♯V / ♭VI (sharp fifth / flat sixth) 
VI (sixth) 
♯VI / ♭VII (sharp sixth / flat seventh) 
VII (seventh) leading tone to the...
I an octave above the start

Counting the semitones from the tonic, these are the same names (without the adjectives like “perfect’) as the musical intervals defined in the previous post.

All the other (equal temperament) scales can be described in terms of this one:

Natural Minor / Aeolian Mode: I-II-♭III-IV-V-♭VI-♭VII
Major Blues: I-II-♭III-III-V-VI
Whole-Tone: I-II-III-♯IV-♯V♯VI

(The ability to recite any other scale or mode in terms of "sharp this, flat that" with utter fluency is an essential skill of any academic or jazz nerd. I'm not sure how much it helps, but it sounds impressive.)

1 comment:

  1. NY: Minor nitpick - the use of Roman Numerals in music theory is only a couple of hundred years or so old (a shorter history than the music they were subsequently used to analyse) and they are used to designate the chords built on the degrees of the scale, and not the notes of the scale themselves. In Jazz Theory arabic numerals are used to describe the intervals of scales relative to their root notes, which has the useful effect to indicating what chords can be built with that structure. The Nashville Numbers system functions in a similar manner to the Roman Numeral System in describing the chords of the scale/key, but using chord symbols based on Arabic numerals.

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