To get the most out of Echo Alpha Delta, you should be familiar with the Number System. It's a language for notes, chords, melodies and scales, which is universal across different keys. Being able to identify the number/function of each note allows us to bend and stretch the Echo Alpha Delta shapes to include any tonality.
Every key in music shares the same internal structure. The Number System replaces note names with numbers, revealing the pattern that all keys have in common. Once you think in numbers, you can instantly transpose anything to any key. With every song you learn, you start recognizing shapes that repeat everywhere.
In any key there is a home note. Every other note has a number relative to it. Each one has its own function, its own effect on the ear. Echo Alpha Delta defines The Number System as two layers: Nashville Numbers for individual notes, and Roman Numerals for chords.
Take any note as your root and call it 1. Every other note gets a number based on its distance from the root. The twelve different notes become:
| Number | 1 | b2 | 2 | b3 | 3 | 4 | #4/b5 | 5 | b6 | 6 | b7 | Maj7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| In C | C | Db | D | Eb | E | F | F#/Gb | G | Ab | A | Bb | B |
| In G | G | Ab | A | Bb | B | C | C#/Db | D | Eb | E | F | F# |
The highlighted numbers (1 2 3 4 5 6 Maj7) are the seven notes of the major scale. The other five are labelled with flats or sharps relative to those scale degrees. Some call these other five "accidentals" but they can really just be seen as different flavours. All 12 notes have their own sound and function.
The Number System shows its usefulness when you start describing tones and melodies as numbers or number sequences and then you're able to instantly translate them into any key.
Chords are usually built with 1, 3 and 5. We can move the chord tones to make a minor chord (1 b3 5), suspended (1 4 5) or more. We can extend the chords upward by stacking on 7ths, 9ths (aka 2nds) 11ths (aka 4ths), 13ths (aka 6ths). They are named high like that in chord structures to represent how they are extending upward rather than simply clustering around the root.
Our Echo Alpha Delta shapes are spelled from the bottom as 1, 5, 1, 3, 5, 1. The higher tones are simple to move around to reach for extended tones and different flavours. Flattening the 3rd (3 to b3) changes the chord to minor. A universe of tonality is accessible.
Chords built on each degree of the major scale get a Roman Numeral. Uppercase means major; lowercase means minor. This is the natural chord map of any major key:
| Numeral | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| Quality | Major | minor | minor | Major | Major | minor | dim |
| In C | C | Dm | Em | F | G | Am | Bdim |
| In G | G | Am | Bm | C | D | Em | F#dim |
| In A | A | Bm | C#m | D | E | F#m | G#dim |
These chords can all be modified. For example v would be a minor chord built on the fifth degree. Chords from outside the key use accidentals: bVII is a major chord built a whole step below the root. bIII is a major chord on the flattened third. A framework can be built off minor or other modes too, like i-ii-III.
Extensions attach directly: V7 is a dominant seventh, IVmaj7 is a major seventh on the fourth degree, Vsus4 is a suspended fourth on the fifth.
Select a key below to see both Nashville Numbers and Roman Numeral chords mapped out for that key.