Definition
A cross-relation (or false relation) occurs when a note and its chromatically altered version appear in two different voices, simultaneously or in consecutive chords. Example: the soprano sings F and, in the next chord, the bass sings F#. The ear perceives a chromatic contradiction (F against F#) that doesn't come from a single melodic line, and this creates a harsh effect.
Why it is avoided (in the classical style)
When the chromaticism stays in the same voice (F → F# in the alto), the ear follows a line rising by semitone: the movement is logical. When instead the F is in one voice and the F# in another, the ear hears two keys contradicting each other. That is why in classical-style voice leading the rule is: the chromatic alteration of a note must occur in the same voice.
How to fix it
- Move the altered note to the voice that had the natural note: instead of F (soprano) → F# (tenor), write F → F# in the soprano.
- If that isn't possible, insert an intermediate chord that separates the two notes.
- When introducing a secondary dominant, check where the note that will be altered sits in the preceding chord (for example the F before D7 in C major).
When it is acceptable
- In minor scales: one voice descends with the natural 6th and 7th degrees (in A minor: A–G–F–E) while another ascends with the raised ones (E–F#–G#–A): this is the natural consequence of using the melodic minor in both directions.
- When one of the two notes is a chromatic passing tone.
- As a deliberate expressive effect: in the Renaissance, and especially in English music of the 16th and 17th centuries, the cross-relation is a typical color.
The English cadence
In the so-called English cadence the lowered 7th degree (in a descending voice) and the leading tone (in another, ascending voice) sound very close together or even at the same time: in G, F natural against F#. Tallis, Byrd and Purcell make it a stylistic trademark.
Practical rules
- Before writing a chromatic chord, look at which voice has the natural note in the preceding chord and give it the chromatic movement.
- A cross-relation between the outer voices is the most noticeable: always avoid it in the classical style.
- In modern arrangements (strings, choir, pads) the same principle applies: if you go from C major to Ab major, have the E fall to Eb in the same voice.
Typical mistakes
- Introducing a secondary dominant with the altered note in a different voice from the one that had the natural note.
- Treating even chromaticism within the same voice as a cross-relation: that is a normal chromatic passing motion.
- Fixing it by moving the voices in a way that creates parallels: you solve one problem and create another.
Examples
- Byrd, “Ave verum corpus”: a G# in the tenor and a G natural in the bass sound together for an instant, a harsh and intentional dissonance.
- Purcell: the English cadences in his operas and anthems are a recognizable trait of his style.
- Bach, in minor passages: the natural 6th and 7th degrees in a descending voice and altered in an ascending voice appear close together.
- Pop arrangements: the C – Ab move (modal interchange) sounds smoother if in the pad the E falls to Eb in the same voice.
How to use it in composition
- Avoid it for a clean, “classical” sound; seek it out on purpose for an archaic, harsh or typically English color.
- In film music, a cross-relation between strings and brass (major against minor) creates unease.
- In a choir, cross-relations are hard to tune: if you use them, write them so that each voice has a logical line.
Exercise
- Write in four voices in C major I – V/V – V with the F of the first chord in the alto and the F# in the tenor; then correct it.
- Write an English cadence in G major with F and F# in two different voices.
- In a C – Ab – Bb – C progression, distribute the voices of a pad so as to avoid any cross-relation.
Related topics
Voice-leading rules; Secondary dominants; Modal interchange; Harmony in minor keys; Chromatic voice leading between chords; Sacred forms: the mass and the motet.