Part Assignment
Who takes the melody, who fills the inner parts, who holds the bass.
Related
The same chords can sound as if every part speaks, or like a wall. The difference is part assignment, meaning who takes the melody, who fills the inner voices, who holds the bass, and who rests.
The problem
When every part sings continuously, the harmony becomes less clear. Assignment means giving each pitch a responsible player and allowing someone to fall silent.
Texture or frequency band
Four-part writing divides the range into four bands. The melody need not stay on top; it can drop into the middle while an upper voice answers. Inner parts are hardest, since they must complete the chord without crowding the melody.
Approach and judgement
Fix the melody's position first, then move the other parts by the nearest interval, avoiding leaps and voice crossing. Similar motion blurs; contrary motion stays clear. If a part repeats chord tones for bars, one bar of rest helps more than another note.
What to listen for
In a choral piece or a slow quartet movement, notice how other parts fall back to long notes when the melody changes instrument. In a homophonic pop song the inner voices are often reduced to one sustained line.
Common misunderstandings
More parts do not mean better part-writing. Four lines all fighting in the top register sound muddier than a clear three-part texture.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Sources
- The New Grove Dictionary of Music and Musicians, 2nd ed., entry Part-writing（Oxford University Press），用于核对声部进行规则
- Walter Piston, Harmony, 5th ed.（W. W. Norton, 1987），用于核对四声部写作与内声部处理
Used for fact-checking only; all prose is original.