False (Cross) Relations
A false (or cross) relation occurs when a note is placed in close time proximity to a chromatically altered version of itself, in another part. For example, if in a flute and piano piece, the flute plays a G natural and a moment later the piano plays a G#, a false relation occurs. When music moves chromatically, it is usually done by step, so the G-G# movement would sound fine played by the same part/instrument. When the chromatic change occurs in different parts or instruments, the effect will be a slight clash or dissonance.
False relations often occur in minor keys, where the notes from the melodic minor scale can cause this type of dissonance, or in any key where there is a lot of chromaticism or fast key changes.
To find a false relation in an exam, scan the score for accidentals. Look for notes of the same letter name with different chromatic alterations, which are written close to each other. A false relation can occur on simultaneous or on successive notes. If two chromatically different notes are written in successive bars, but not successive beats, there will be enough “space” between them to prevent a clash, and they will not be considered to be false relations.
In the fourth bar of this extract (Chopin’s Cello Sonata) there is a false relation between the Ab in the cello part, and A naturals in the piano part.