Do seventh chords add vocal pitches not found in triads?
maj7 in the chord adds a tone that is part of the vocal melody and that tone is not part of a plain triad.
7 on these chords are not in the vocal part.
Would this song [The Girl From Ipanema] not have been possible with regular triads..?
It would have been "possible" in so far as an accompaniment of a plain
F major triad plus the vocal part providing an
E would combine to realize the
So you might ask "why add chord extensions to the accompaniment in a lead sheet if the vocal part already provides the extensions?"
I can think of three reasons:
- A piano or guitar is probably assumed to part of the accompaniment in jazz and a composer or arranger wants the full sonority of extended chords on those intruments, in other words plain triads on piano or guitar don't really have the jazz sound.
- The chords are used to accompany a soloist, you may not be assured the soloist will hit all chord extensions in a solo, so the accompaniment needs to play the full chords.
- Singers often 'interpret' melodies and don't sing them exactly as written, you can't rely on a singer to provide all the extensions, the accompaniment must play full chords.