what does jazz music include the seventh chord as the basic harmonic building block?
Because seventh chords have a more complex sound than triads and support extensions of chords, (9,11,13) that characterise jazz language
What are the three basic functions that define major key harmony?
The tonic, subdominant, dominant
what does the word “function” mean in relation to chords?
The term “function” describes a chords stability relative to other chords within a piece of music, as well as its potential to progress in a certain manner within a given phrase
What is the function of the tonic?
- To provide a stable point of departure and return
- the term tonic expresses the idea that one note or tone serves as the fundamental reference and central point of rest in a piece or section of a piece
what is the primary tonic chords of major key jazz harmony?
IMaj7 / IMaj6
What is the function of the subdominant?
- to create contrast with the tonic (IV-I, I-IV, I-IV-I), or to prepare for the dominant (IV-V)
Where is the subdominant positioned in relation to the tonic?
A perfect 5th below the tonic
Why is tension created from a IMaj7-IVMaj7 transition?
- the root of the IV chord is the least stable note of the key; it tends to lead strongly back to 3 (Fa-Mi)
- in addition, the 3 of the IVMaj7 chord is also an unstable tone in the key, scale degree 6 tends to move back to 5 (La-Sol)
Why is the subdominant to tonic motion not as powerful as dominant resolution?
- The IV chord lacks the leading tone, scale degree 7
- The IV chord is more closely related to the tonic triad by an important common tone, the tonic note itself
- The root motion of the subdominant chord back to the tonic is a perfect fifth ascending (or perfect fourth descending) rather than vice verse
What is the function of the dominant chord?
to cause the listener to expect resolution to the tonic
How is the expectation of the function of the dominant to tonic chord created?
- this expectation is created by the vertical combination of unstable scale tones in the V7 chord - in particular, the interval of a tritone (augmented 4th or diminished 5th) created by scale degrees 4 and 7
What is significant about the tritone in a V7 chord?
- the sound of a tritone is the defying characteristic of the dominant 7
What are the resolving unstable tones in a V7-IMaj7 progression?
- The unstable tones in the V7 gain the resolution in the IMaj7 chord going from 2-1 and 4-3
- the root of the V7 moves down by an interval of a perfect 5th to anchor the resolution
What is significant about the V7sus4 chord in its flexibility of function?
- When V7sus4 precedes a V7, it sounds subdominant, a suspension before the dominant
- e.g. V7sus4 - V7 - IMaj7
- however, when V7sus4 directly precedes a tonic chord, we accept it as a substitute for the V7 chord even though it doesn’t contain the interval of a tritone
What is an example of the V7sus4 chord acting as a dominant function?
- II-7 - V7sus4 - IMaj7
- D minor 7 - G7sus4 - C major 7
- The root motion by a perfect fifth as well as the dissonant minor seventh interval between its root and seventh provide enough information in this context to create the expectation of resolution to the tonic
