In reference to
voice leading in four-part harmony (
SATB), close and open structures refers to the relative spacing and voicing
considerations of the chords.
- Open Structure: A voicing is considered to be of an open structure when an interval of an octave or more occurs between the soprano and tenor voices.
- Close Structure: A chord is considered to be of a close structure when the interval between the soprano and tenor voices is less than an octave.
This is a generally accepted
terminology among
musicologists and
musical theorists, and should be recognized as such when used in
conversation or
analysis.