4.3. The relationship between root progressions and musical phrases
4.3.1. Phrase Structures
So far so good, but there is still more to read from the root progressions. As chord progressions have these properties clearly and consistently across many pieces of music then there must be some reason for this. In order to try and understand the possible reason, we could try and establish if there is a relationship between chord progressions and musical phrases.
As there is no ready made theoretical basis (known to me) for delimiting musical phrases, for the purpose of this analysis, I'll define a musical phrase as follows:
- That unit which starts at the beginning of a piece or end of a previous phrase and ends with a perfect cadence is a complete phrase.
- That unit which starts at the beginning of a piece or end of a previous phrase and ends with an imperfect cadence is an incomplete phrase.
- Phrases may overlap. In this situation the final tonic of the cadence becomes the tonic of the ensuing phrase.
This definition, whilst not covering all possibilities, is adequate for most situations and forms as objective and simple a definition as is possible and is selected here for this reason. Where cadence structures are not sufficiently clear to absolutely define the phrase endings then it is appropriate to examine the motivic structure of the music to help clarify the delineation of the musical phrases. For a more complete definition of a musical phrase as used in Syntactic Structures in Music please refer to the glossary.
I've listed out all the chord progressions in appendix C. This shows bar numbers and page numbers for reference to the musical score in appendix B. I've also shown phrase numbers at the start of each phrase. Included are some notes showing the formal significance of each of the phrases. Finally, I've highlighted the clustering of paired and non-paired progressions by a colour scheme as follows: (pale versions of the colours are used as backgrounds in the list)
| Green |
This indicates clusters of paired progressions where the main chord is the tonic chord. These constitute static harmony based on the oscillation of the tonic with other chords. These could be described as tonic prolongations as the tonic is prolonged without underlying root movement. |
|
Blue |
This indicates clusters of paired progressions where the main chord is the dominant chord. These constitute static harmony based on the oscillation of the dominant with other chords. These could be described as dominant prolongations as the dominant is extended without underlying root movement. The presence of the minor 7th addition to the chord often indicates a dominant rather than tonic prolongation. |
| Red | This indicates a cluster of non-paired progressions. These clusters constitute dynamic harmony as they are made up of strong root progressions. |
The progression clusters thus create the segmentation that is necessary to divide the musical phrases into syntactic elements.
The phrase structures in the Mozart example may be summarised as follows:
The movement is in sonata form with two main subjects and a codetta. The first phrase (the first subject) extends from bar 1 to 8 and the cadence overlaps into the second phrase at bar 9. This is an extended repeat of the first phrase and ends on an imperfect cadence at bar 22. The third phrase (the second subject) starts at bar 23 and ends with a perfect cadence at bar 35. At bar 35 starts phrase 4 which is the codetta subject which overlaps with the perfect cadence of the second subject. After 5 bars of this phrase there is a slightly altered repeat of it (phrase 5) at bar 40 (perfect cadence pattern, overlapping again) This phrase extends to the end of the exposition which concludes with a perfect cadence. This is the first perfect cadence which is complete and without overlapping. Sometimes, the way the phrases overlap makes the phase structure difficult to determine. In this way, phrase 5 could be subdivided into two phrases at the cadential pattern at the end of bar 44 but the consistency of the motivic content suggests that this unit constitutes one phrase.
This brief summary highlights some of the issues when dividing music into phrases and shows how I have tried to tackle this in as objective a way as possible. The development section and recapitulation have been divided up by similar means as indicated in appendices B and C. Appendix D which contains a full commentary on the analysis.
We now have two separate analyses of the example - one of root progression patterns and one of phrase structures. Examination of the colour banding shows a clear relationships between root progression patterns and phrase structures, as follows:
- Cluster boundaries occur at all phrase boundaries (whether the cadences are perfect, imperfect or overlapping)
- There is a regularity in the pattern of banding. There are only three phrase patterns in evidence, in this piece:
| Green - Red | tonic based static harmony - dynamic harmony | 5 phrases |
| Green - Red - Blue | tonic based static harmony - dynamic harmony - dominant based static harmony | 4 phrases |
| Red only | dynamic harmony only | 3 phrases |
These patterns are confirmed as common patterns by analysis of many other pieces of music. The three patterns can be related as follows: The green - red pattern can be described as the basic pattern, the green - red - blue pattern as an extension to the basic pattern by prolonging the final dominant of the dynamic harmony and the red only pattern as an incomplete form of the basic pattern. Analysis of many other examples indicates that there are other ways of extending the basic pattern but all extended forms are derived from the same basic pattern. (See Syntactic Structures in Music)
If we include the cadences and show these patterns in diagrammatic form we get the following: This type of representation is usually referred to as parsing.
The basic structure: (Green / Red)
The basic structure contains all the elements to make complete sense in the musical phrase, i.e: static harmony, dynamic harmony and a complete perfect sentence. Please refer to the demo section of this web site for examples and also to the book summary
An extended structure: (Green / Red / Blue)
This extended structure contains all the elements that are present in the basic structure but in addition, the dominant of the cadence is extended into a dominant prolongation, created by static harmony around the dominant chord. Please refer to the demo section of this web site for examples of this and other types of phrase extension. Also, please refer to the book: Chapter 5. Extensions within the Basic Structure
An incomplete structure, as follows: (Red only)
This incomplete structure shows the same structure as the closing section of a complete phrase, i.e. it has dynamic harmony and a complete perfect cadence. It can also be expanded in all the ways that a closing section can i.e. by the expansion of the cadential dominant into a dominant prolongation and/or the expansion of the credential tonic into a static coda.
Each of these structures may terminate on chord I; overlap with a subsequent phrase or may end on an imperfect cadence (i.e. final I absent).
It is this alternation between static and dynamic forms of harmony that is the key to the structure of musical phrases.