About notes, chords, horizontal, vertical and modal scales


The term Pitch refers to the frequency of a tone. Music theory is mainly organized around Pitch Class though, which implies a pitch and all its possible octave transpositions. That is, if we talk of Bb or D# what is really meant is a pitch class rather than a frequency. Some ideas of music theory can't be explained without distinguishing these notions.

In order to keep it simple, we use the term Note synonymously for both Pitch and Pitch Class depending on context.

  1. Note means pitch class, when we talk about chords, scales and harmony in general.

  2. Note means pitch (frequency) with a duration, when we talk about pitch ranges, instruments and sounds.

Note: For display and parsing, specific naming conventions apply.


When multiple notes happen to sound at the same time, we have a Chord. When these notes are sorted by pitch class, starting from the chord's Root pitch, we get the Interval Structure that lends the chord its name. The sound of a chord can be varied by Inversion (ordering of intervals) and Voicing (overall octave range).

Chords consist of a basic Triad of three notes plus optional Extensions. These are intervals added to make it more complex, rich and ambiguous. For example the basic triad Am can be extended as Am6, Am7, Am9, Am11 or Am(6,9,#7) and many more.

Note: For display and parsing, specific naming conventions apply.


A Scale is a series of Notes starting from a Root note upwards. Most scales in Western music repeat every octave. The timbre and character of a scale is determined by its Interval Structure, the distances between its notes measured in halftones.

Examples for scales widely used in Western music are Major, Natural Minor, Melodic Minor, Harmonic Minor. There are scales with seven steps (septa-tonic scales), or five (pentatonic), or any other number. A scale with twelve tones in halftone intervals is called the Chromatic Scale. It is equivalent to all keys on a piano keyboard.

Synfire distinguishes between Vertical Scales and Horizontal Scales, which are physically the same thing, but take on separate roles and are thus traditionally labeled differently. That is, the same physical scale often has a different name depending on its role.

E.natural-minor (horizontal) = E.aeolian (vertical)
Note: For display and parsing, specific naming conventions apply.

Vertical Scale

The Vertical Scale provides notes for melodic ornaments and improvisation. For each chord, a vertical scale can be picked according to preference and style. It is named vertical because its notes are stacked vertically above the current chord. Both, the chord and the vertical scale, start at the same root. It is important to remember that the vertical scale changes with every chord.

The vertical scale determines which notes are allowed for building melodies over a chord. Some may be outside the Horizontal Scale, if only the duration of the chord. Vertical scales are particularly important for improvisation. A musician may play up and down the scale and be assured that it fits the chord, although that alone doesn't make a good melody, of course.

Countless vertical scales exist, originating from various eras, cultures, and music genres. A selection of the most commonly used scales is included with the Catalog of Synfire, to which you can add more scales as needed.

Horizontal Scale

While the vertical scale is tied to a chord and therefore constantly in motion, the Horizontal Scale is meant to continue unchanged for a longer period of time. It is strongly tied to a Key, denoting its steps I, II, III, IV, V, VI, VII (German: "Tonleiter"). Melodies built on the horizontal scale move across multiple chords more evenly, even though the vertical scales over each chord may temporarily extend or reduce the set of allowed notes.

A horizontal scale starts with the root note of the Key. It belongs to the Scale Set of the key. Traditionally, only a few scales are used as horizontal scales. These are the well-known major and minor scales and their variants.

Mode (Modal Scale)

Some scales are used both as vertical scales for improvisation and melody construction (with jazz, in particular) as well as horizontal scales. These so-called "church modes" were introduced with modal music early in music history and are still widely used.

Figure 1. Scale A.Phrygian-Dominant = Mode 5 of D Harmonic-Minor.

Modes are basically rotations of major or minor scales and are therefore physically equivalent with them although not identical.

Major: Minor:
Major Natural minor Melodic minor Harmonic minor
  1. Ionian

  2. Dorian

  3. Phrygian

  4. Lydian

  5. Mixolydian

  6. Aeolian

  7. Mixolydian

  1. Aeolian

  2. Locrian

  3. Ionian

  4. Dorian

  5. Phrygian

  6. Lydian

  7. Locrian

  1. Melodic

  2. Dorian b2

  3. Lydian augm.

  4. Lydian b7

  5. Aeolian major

  6. Locrian #2

  7. Super locrian

  1. Harmonic

  2. Locrian 6

  3. Ionian augmented

  4. Dorian #4

  5. Phrygian dominant

  6. Lydian #2

  7. Altered dominant bb7

The modes listed here are only a small selection of the built-in catalog. In addition, there are the corresponding modes of melodic major, harmonic major, hungarian major, and hungarian minor.

Modes that arise from arbitrary horizontal scales are computed by Synfire only as needed and are automatically assigned a suitable name.