[Smt-talk] Sequences

[Dmitri Tymoczko]

> Another example of a sequence where the typical part-writing is  
> opposite the smoothest idealized voice leading is the ubiquitous  
> descending fifth sequence. We usually associate descending part  
> writing with the descending fifths sequence, but it has idealized  
> ascending voice leading.

This is an important point.

In "strong" progressions, the root moves (diatonically) by descending  
third, descending fifth, or ascending step.  When you're using plain  
triads, the most efficient voice leading for a strong progression is  
ascending.  This creates a conflict between two tonal imperatives: 1)  
using efficient voice leading, and 2) creating phrases that use  
descending melodic contours.  (Hello, Heinrich, nice to see you  
again!)  Typically, then, a harmonic cycle such as I-IV-V-I or I-ii-V- 
I involves at least one non-minimal voice leading.  The descending  
fifth sequence is a case in point -- usually one of the two voice  
leadings is non-minimal, as in (C, E, G)->(C, F, A)->(B, D, F)->(B,  
E, G), where the nonminimal voice leading is (C, F, A)->(B, D, F).

With seventh chords, the situation is reversed -- now the most  
efficient voice leadings for strong progressions descend.  This means  
that you can create sequences, or harmonic cycles, using maximally  
efficient descending voice leadings.  You start to see this more and  
more often in nineteenth-century music, and it eventually becomes  
central to jazz voice-leading practice.

DT

Dmitri Tymoczko
Associate Professor of Music
310 Woolworth Center
Princeton, NJ 08544-1007
(609) 258-4255 (ph), (609) 258-6793 (fax)
http://music.princeton.edu/~dmitri





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