Roman numeral analysis allows you to classify chords based on their scale degree and quality. Scale degrees of roots are indicated by capital Roman numerals; chord qualities are written above with special symbols like an “o”, “+”, or “v”.
Major chords use uppercase roman numerals while minor chords require lowercase Roman numerals.
Major Triads
Roman numeral chord analysis involves identifying major, minor and diminished chords within a key by studying its scale degree sequence. After this has been accomplished, each triad’s quality can be determined using its chord-quality pattern within that major scale.
Example: Triads with G# in their root will be major; those containing a B in their roots are minor. This process works by counting how many half-tones (or semitones) separate each scale degree and its respective triad.
An additional symbol is used to indicate whether a seventh chord is in its diminished or augmented state, by appending either an “o” or “+” symbol to its name; for instance “viio” denotes a diminished seventh chord while “v7” stands for dominant seventh chords – this system can prove particularly helpful when using tonic-dominant progression in music compositions.
Minor Triads
If a chord is constructed using the minor scale, its Roman numeral will be lower-case and can either be increased or decreased depending on whether its composer uses either harmonic or melodic minor scales. For instance, in minor keys with seven chords it would normally be VII; when using harmonic minor scales its Roman numeral becomes vii instead.
As scale degree numbers remain the same but triad chord quality differs, this can be confusing. To help keep track of things, review the triad chord table and count how many half-tones exist between root note and each note of triad chord.
Use the Roman numeral table to identify triads within your scale by assigning Roman numerals for them in Roman numeral form. Additionally, add letters (such as VIIa or VIIb or VIIc ) before writing their Roman numeral to see different inversions of these triads.
Major Sevenths
diatonic seventh chords use Roman numerals to represent major and minor triads, respectively. An added “7” after each roman numeral denotes there is a minor seventh between root and seventh of a chord; examples would include VV7 or vivi7 as examples of this situation.
Contrary to triads, where notes in the bass voice must often be doubled up in the upper voices, seventh chords do not require this form of duplicating notes in their bass voice in order to form them correctly. However, leading tones (those which appear above a triad’s root note) should never be doubled, nor tension tones which appear above or below it be doubled; tension tones must instead be marked with an “e” to indicate their use as tension tones.
At the start of a piece, it is often useful to identify its key and then use Roman numerals throughout to describe how the chords stack in that key. Sometimes however, it is more helpful to identify chord quality by writing “m” after the Roman numeral or adding an o or (m). Sometimes this is combined with roman numerals describing scale degree (vii(7)), so the chord may also have its name changed accordingly.
Minor Sevenths
When a seventh chord is composed by building on a minor scale degree, its lowercase Roman numeral is assigned. The quality of this chord depends on what kind of triad has been formed which could either be major, minor, diminished (lowered 5th), or augmented (raised 5th). A diminished or augmented chord will be marked iv7 or vi7 accordingly.
When using Roman numerals for modal alterations, an accidental should always precede each numeral to prevent confusion and ensure efficiency. This will also help avoid any instances of transpositions being misread as literal numbers.
As well, it is important to keep in mind that Roman numerals for triads and sevenths don’t always work best. For instance, melodic minor’s raised sixth scale degree known as subtonic calls for its chord symbol to simply read as vi7 for ease of reading purposes and clear differentiation from major seventh chords.