[6] During the common practice period of Western classical music, composers orchestrating chords that are voiced in four or fewer parts would select which notes to use so as to give the desired sonority, or effect of the intended chord.
Generally, priority was given to the third, seventh and the most extended tone, as these factors most strongly influence the quality and function of the chord.
[9] Following standard voice leading rules: An important distinction between extended and added chords must be made, since the added tones and extended tones are enharmonic, but differ in function.
[14] The theory of supposition was adopted and modified by Pierre-Joseph Roussier, Friedrich Wilhelm Marpurg, and other theorists.
A. F. C. Kollmann, following Johann Kirnberger, adopted a simpler approach and one closer to that prevalent today, in which Rameau's "supposed" bass is considered the fundamental and the ninth and eleventh are regarded as transient notes inessential to the structure of the chord.
[15] In 19th-century classical music the seventh chord was generally the upper limit in "chordal consonance", with ninth and eleventh chords being used for "extra power" but invariably with one or more notes treated as appoggiaturas.
[12] The "piling up" of thirds above the tonic to make seventh, ninth, eleventh, or even thirteenth chords "is one of the most important characteristics of jazz harmony".
In these genres, chords often include added ninths, elevenths and thirteenths as well as their altered variations.