Tone and Voice:A Derivation of the Rules of

Voice- Leading fromPerceptual Principles

DAVID HURON

Music Perception 2001, 19, 1-64

Voice Leading

The manner in which individual parts orvoices move from tone to tone tocreate perceptually independentmusical lines.

Rules of voice leading1. Registral Compass Rule: Write in the region

between F2 and G52. Textural Density Rule. Harmony should be

written using three or more concurrent voices.3. Chord Spacing Rule.

soprano - alto =< octavealto-tenor =< octavetenor - bass no restriction.

4. Avoid Unisons Rule. Avoid concurrent unison5. Common Tone Rule. Pitches common to

consecutive chords should be retained in thesame voice.

Rules (2)6. Nearest Chordal Tone Rule. Move to the nearestavailable pitch.7. Conjunct Motion Rule. If possible by a diatonicstep. Or, expressed in reverse:8. Avoid Leaps Rule. Avoid large melodic intervals.9. Part-Crossing Rule. Pitch contours should notcross.10. Part Overlap Rule. No part should move to amore extreme pitch higher than the immediatelypreceding pitch in another part.

Rules (3)11. Parallel Unisons, Fifths, and Octaves Rule. Notwo voices should move in parallel octaves, fifths, orunisons. Some even say:12. Consecutive Unisons, Fifths, and Octaves Rule.None even if not parallel.13. Exposed (or Hidden or Direct) Octaves (andFifths) Rule. Bass and soprano voices should notapproach octaves by similar motion between twoparts unless at least one of the parts moves bydiatonic step.

Perceptual principles1. Toneness Principle.Strong auditory images are evoked

when tones exhibit a highdegree of toneness or virtualpitch weight eg Harmoniccomplex tones between F2 andG5.

1. Toneness Principle.

2. Principle of Temporal Continuity.

In order to evoke strong auditory streams,use continuous or recurring rather than briefor intermittent sound sources. Intermittentsounds should be separated by no more thanroughly 800 ms of silence in order to ensurethe perception of continuity.

But avoid overlapping sounds as in normalpiano or gamelan (tutupan) performance.

3. Minimum Masking Principle

Approximately equivalent amounts of spectralenergy should fall in each critical band / auditoryfilter. For typical complex harmonic tones, thisgenerally means that simultaneously soundingnotes should be more widely spaced as the registerdescends.

Width of auditory filters

3. Minimum Masking Principle

4. Tonal Fusion Principle

To maintain independence avoid intervalsthat promote tonal fusion eg:

unisons, octaves, perfect fifths

Fusion and consonance

* * *

5. Pitch Proximity Principle.

The coherence of an auditory stream is maintained byclose pitch proximity in successive tones within thestream.Pitch-based streaming is assured when pitchmovement is within van Noorden’s fission boundary(region 1 - normally 2 semitones or less for tones lessthan 700 ms in duration).When pitch distances are large, it may be possible tomaintain the perception of a single stream by reducingthe tempo.

5. Pitch Proximity Principle

5. Pitch Proximity Principle

5. Pitch Proximity Principle

? Bach notes shorter since harpsichord not continuous ?

5. Pitch Proximity Principle

demo on Bregman CD track 17

Failure to perceive crossing explained by pitch proximity.

6. Pitch Co-modulation Principle.

The perceptual union of concurrent tones is encouragedwhen pitches move together maintaining constant ratios.

Darwin, Ciocca & Sandell, 1994 JASA showed that amistuned harmonic continued to contribute to pitch withgreater mistuning when coherent FM than when none.

Bregman micro-mod track 24.

7. Onset Synchrony Principle.To keep parts independent, avoid note onsetsof less than 100ms.

8. Principle of limited densityTo keep parts independent, have 3 or fewerparts.

9. Timbral differentationTo keep parts independent, have uniquetimbres

See also:Bregman CD demo 9

Culling, J. F. and Darwin, C. J. (1993). "The role of timbre in thesegregation of simultaneous voices with intersecting Focontours," Percept. Psychophys. 34, 303-309.

10. Spatial differentationTo keep parts independent, have themspatially separated.

Bregman demo of streaming by spatial location in East Africanxylophone music. Demo 41.

Sach, A. J. and Bailey, P. J. (2004). "Some characteristics ofauditory spatial attention revealed using rhythmic maskingrelease," Percept Psychophys 66, 1379-87.