Understanding Move Properties in Orphere: Voice Leading, Triadic Distance, and More
Harmony isn’t just about individual chords and scales. It’s about what happens between them. The tension when you move from a major chord to a minor one. The smoothness of a modulation that shares five common tones. The dramatic lift when brightness shifts upward.
Orphere analyses every possible transition between scales and between chords, and gives you a set of move properties that describe exactly what’s happening in the journey from A to B. This post explains what each one means and how to use it when composing.
The anatomy of a move
When you place a scale or chord in Slot A and browse candidates for Slot B, Orphere calculates a move for every candidate. Each move contains:
- Classification: what kind of harmonic movement it is
- Shared material: what they have in common
- Distance properties: how far apart the two harmonies are
- Colour shifts: how the character changes
These properties work together. A move with low voice leading distance and high common tones will feel smooth. One with a large brightness shift and high triadic distance will feel dramatic. The filters in Orphere let you search for exactly the type of transition you want.
Properties at a glance
| Property | Category | Applies to | What it measures |
|---|---|---|---|
| Move type | Classification | Chords and scales | The quality-semitone-quality code for the transition (e.g. M7m) |
| Move class | Classification | Chords and scales | The broader harmonic category the move type belongs to |
| Cadence type | Classification | Regions | The functional cadence category (authentic, half, deceptive, plagal, indefinite) |
| Common tones | Shared material | Chords and scales | The notes shared between the two harmonies |
| Similarity | Shared material | Chords and scales | The degree to which pitch class sets overlap |
| Semitone shift | Distance | Chords and scales | The raw semitone count between the two roots or tonics |
| Interval shift | Distance | Chords and scales | The musical interval between the two roots or tonics |
| Circle of fifths distance | Distance | Chords and scales | The number of perfect fifth steps between the two roots or tonics |
| Triadic distance | Distance | Chords with a third degree | The neo-Riemannian distance between the two implied triads, from 0 to 5 |
| Voice leading distance | Distance | Chords and scales | The minimum total semitones voices must move between harmonies |
| Affect shift | Composite | Chords and scales | The emotional trajectory between the two harmonies |
| Brightness shift | Colour shift | Chords and scales | The change in brightness |
| Unevenness shift | Colour shift | Scales only | The change in how evenly the step sizes are distributed |
| Dissonance shift | Colour shift | Chords only | The change in acoustic tension as defined by dissonance |
| Complexity shift | Colour shift | Chords and scales | The change in complexity as defined by interval rarity |
| Uniqueness shift | Colour shift | Scales only | The change in uniqueness as defined by degree rarity |
Move type and move class
Every move between two chords or two scales is assigned a move type, a compact code that encodes three things: the quality of the source, the semitone distance between the roots, and the quality of the destination. The format is:
source quality + semitone shift + destination quality
For example, M7m means a move from a major harmony (M) up 7 semitones to a minor harmony (m). m3M means minor up 3 semitones to major. The quality symbols are M (major), m (minor), and o (other, no third).
Move types are grouped into move classes that describe broader harmonic categories:
| Move class | Move types | Description |
|---|---|---|
| Ionian MXM | M0M, M5M, M7M | Major-to-major moves along diatonic intervals |
| Sharp-degree MXM | M11M, M4M, M9M, M2M | Major-to-major moves by sharp-side intervals |
| Flat-degree MXM | M1M, M10M, M6M, M8M, M3M | Major-to-major moves by flat-side intervals |
| Ionian MXm | M2m, M9m, M4m | Major-to-minor moves along diatonic intervals |
| Sharp-degree MXm | M6m, M1m, M11m | Major-to-minor moves by sharp-side intervals |
| Flat-degree MXm | M10m, M7m, M5m, M0m, M8m, M3m | Major-to-minor moves by flat-side intervals |
| Aeolian mXM | m3M, m10M, m8M | Minor-to-major moves along diatonic intervals |
| Sharp-degree mXM | m2M, m5M, m7M, m9M, m0M | Minor-to-major moves by sharp-side intervals |
| Flat-degree mXM | m6M, m4M, m11M, m1M | Minor-to-major moves by flat-side intervals |
| Aeolian mXm | m0m, m5m, m7m | Minor-to-minor moves along diatonic intervals |
| Sharp-degree mXm | m11m, m2m, m6m, m4m, m9m | Minor-to-minor moves by sharp-side intervals |
| Flat-degree mXm | m1m, m8m, m3m, m10m | Minor-to-minor moves by flat-side intervals |
| Any MXo | M0o–M11o | Major-to-other moves (all 12 semitone distances) |
| Any oXM | o0M–o11M | Other-to-major moves (all 12 semitone distances) |
| Any mXo | m0o–m11o | Minor-to-other moves (all 12 semitone distances) |
| Any oXm | o0m–o11m | Other-to-minor moves (all 12 semitone distances) |
| Any oXo | o0o–o11o | Other-to-other moves (all 12 semitone distances) |
When to use it: Move type and class give you a way to think about harmonic motion categorically. If you know you want to stay within diatonic major-to-major relationships, filter for “Ionian MXM”. If you want to explore minor-to-major shifts by unusual intervals, look at “Sharp-degree mXM”. These classifications also connect directly to triadic distance, since each move type maps to a specific triadic distance value.
Cadence type (region moves only)
When both the scale and chord change together (a full region move), Orphere identifies the cadence type based on the functional relationship between the two chords within their scales:
- Authentic: Dominant to tonic (V to I). The strongest resolution.
- Half: Any chord moving to the dominant (to V). Creates expectation.
- Deceptive: Dominant to a non-tonic chord (V to vi, V to IV, etc.). Subverts expectation.
- Plagal: Subdominant to tonic (IV to I). The “amen” cadence.
- Indefinite: Anything that doesn’t fit the above categories.
When to use it: Cadence detection helps you build progressions with intentional phrasing. If you want a passage to feel resolved, look for authentic cadences. If you want to keep things moving, use half cadences to create forward momentum. Deceptive cadences are powerful tools for delaying resolution.
Common tones
Common tones are the notes shared between two harmonies. Orphere lists them explicitly, including enharmonic equivalents (so if Scale A has C# and Scale B has Db, you’ll see “C#=Db” in the list).
The number of common tones is closely related to voice leading distance, but they measure different things. Two chords can share most of their notes but still require a large voice leading movement if the non-shared notes are far apart.
When to use it: Common tones are the glue in modulations. When you’re writing a transition between two key areas, shared notes give the listener something to hold onto. Filter for moves with a high common tone count when you want a passage to flow. Filter for low counts when you want contrast.
Similarity
Similarity is the Jaccard index of the two pitch class sets: the number of shared pitch classes divided by the total number of unique pitch classes across both harmonies.
A similarity of 1 means the two harmonies contain exactly the same pitch classes. A similarity of 0 means they share nothing. Most practical moves fall somewhere in between.
When to use it: Similarity gives you a single number for “how alike are these two harmonies?” It’s useful for controlling the pace of harmonic changes and modulations throughout a progression.
Semitone shift and interval shift
The most basic description of a move is the interval between the two roots (for chords) or tonics (for scales).
Semitone shift gives you the raw number: 7, 3, 6. Interval shift gives you the musical name: a perfect fifth, a minor third, a tritone. Both describe the same thing from different angles.
If you’re thinking in terms of key relationships, interval shift is your guide. Moving up a perfect fifth (semitone shift 7) from C takes you to G, the dominant. Moving up a minor third (semitone shift 3) takes you to Eb, the mediant.
Circle of fifths distance
Circle of fifths distance counts the number of perfect fifth steps between two roots or tonics. C to G is 1, C to D is 2, C to Eb is 3 (moving in the flat direction).
Keys that sit close together on the circle share most of their notes, which is why voice leading distance and similarity tend to correlate with circle of fifths distance. It’s the traditional way theorists describe key relatedness.
When to use it: If you want a modulation that stays within tonal neighbours, filter for low circle of fifths distance. If you want a distant key change, look for higher values. This pairs well with voice leading distance: two keys can be far apart on the circle but still connected by smooth voice leading, or close on the circle but requiring large voice movements.
Triadic distance
Triadic distance measures how harmonically related two triads are. Each chord with a third degree implies a triad (the root, third, and fifth), and the distance between those two triads is calculated from the combination of their qualities (major or minor) and the interval between their roots. It ranges from 0 (same triad) to 5 (distantly related).
Some examples:
- Distance 0: C major to C major (no change)
- Distance 1: C major to A minor (relative minor), C major to C minor (parallel minor)
- Distance 2: C major to Eb major (chromatic mediant)
- Distance 5: C major to F# minor (distantly related)
Triadic distance is rooted in neo-Riemannian theory, which maps the relationships between triads through transformations like relative (R), parallel (P), and leading-tone exchange (L). It captures these relationships as a single number.
When to use it: Low triadic distance gives you moves that sound functionally related. High triadic distance gives you moves that feel like a departure. This is useful when planning the large-scale harmonic structure of a piece.
Voice leading distance
Voice leading distance measures the minimum total number of semitones that voices need to move to get from one harmony to another. Notes don’t need to map one-to-one between the two harmonies: they can be added, dropped, or shared.
A voice leading distance of 0 means the two harmonies contain exactly the same pitch classes (even if spelled differently). A distance of 1 means only one voice moves by one semitone. Higher values indicate more movement.
When to use it: This is arguably the most practical move property for composition. Low voice leading distance creates smooth, connected progressions. If you want a modulation that feels seamless, filter for candidates with voice leading distance of 1 or 2. If you want a bold harmonic shift, look for higher values.
Affect shift
Affect shift describes the emotional trajectory of a move using two values: affectFrom and affectTo. Every move class has an associated affect shift, and the two values together define the overall emotional character of the move. Positive values represent brighter, more uplifting affect. Negative values represent darker, more introspective affect. Values near zero are neutral.
For example, a move from C major to A minor (M9m, Ionian MXm) has affectFrom +3 and affectTo -2, a strong shift from positive to negative. A move from C minor to Eb major (m3M, Aeolian mXM) has affectFrom -3 and affectTo +2, a strong upward shift.
When to use it: Use affect shift to shape the emotional direction of your progressions. If you want a passage to grow happier or more uplifting, look for moves where affectTo is higher than affectFrom. If you want things to darken or grow sadder, look for the opposite. Filtering by affect shift lets you control the emotional arc of your music deliberately rather than by trial and error.
Brightness shift
Brightness shift is the difference in brightness between the destination and the source. A positive shift means you’re moving to something brighter (more raised degrees). A negative shift means you’re moving darker (more lowered degrees).
For scales, this captures the familiar brightness ordering of modes. Moving from aeolian to dorian is a small positive brightness shift. Moving from ionian to phrygian is a large negative one. For chords, the same principle applies. Moving from a minor triad to a major triad brightens the harmony.
When to use it: Brightness shift is essential for controlling the emotional arc of a passage. If you’re building towards a climax, look for positive brightness shifts. If a scene needs to darken gradually, chain moves with small negative shifts. If you want harmonic movement without changing the mood, filter for brightness shift near zero.
Unevenness shift (scales only)
Unevenness shift measures how the distribution of intervals within the scale changes. Moving from a major scale (low unevenness) to a harmonic minor scale (high unevenness, due to the augmented second) produces a positive unevenness shift.
When to use it: This property affects the melodic character of your writing. If you want the melodic feel to stay consistent across a modulation, keep unevenness shift close to zero. If you want a transition to introduce a new melodic flavour (the exotic gap of a harmonic minor, for instance), look for a positive shift.
Dissonance shift (chords only)
Dissonance shift measures the change in acoustic tension between two chords. A positive shift means the destination chord is more dissonant. A negative shift means it resolves to something more consonant.
When to use it: This is the tension-and-release control. Building towards a climax? Look for positive dissonance shifts. Writing a resolution? Filter for negative shifts. Paired with brightness shift, you can create moves that brighten while resolving, or darken while tensing, giving you fine control over the emotional direction.
Complexity shift
Complexity shift measures how the tonal interval class content changes between two harmonies. Moving from a scale or chord built on common intervals (low TIC values, like fifths and thirds) to one with tonally distant intervals (high TIC values, like tritones) produces a positive shift.
When to use it: This helps you control how adventurous the harmonic language feels across transitions. A complexity shift near zero keeps things in the same intervallic territory. A large positive shift introduces intervals that are further from the tonal centre of the circle of fifths, which can signal a change in scene or character.
Uniqueness shift (scales only)
Uniqueness shift measures how the distance from standard major or minor patterns changes. Moving from ionian to double harmonic major produces a large positive uniqueness shift.
When to use it: Similar to complexity shift but focused on how “exotic” the scale feels relative to common tonal patterns. Use it to control how far you’re venturing from familiar territory.
Combining move properties
The real power of move properties is in combining them to describe exactly the kind of transition you want:
-
“A smooth modulation that darkens the mood”: Filter for low voice leading distance, high common tones, and negative brightness shift.
-
“A dramatic key change that feels related”: Filter for low triadic distance but high semitone shift. The harmonic relationship keeps things connected, but the root movement creates impact.
-
“A resolution that releases tension”: Filter for negative dissonance shift and an authentic cadence type.
-
“Something unexpected but not jarring”: Filter for high similarity (shared notes keep it grounded) but a deceptive cadence type (the functional relationship surprises).
Every move property in Orphere describes something you can hear in the transition. Together, they give you a vocabulary for searching not just for chords and scales, but for the connections between them.