In jazz chords and theory, most triads that appear in lead sheets or fake books can have sevenths added to them, using the performer's discretion and ear.
[2] However, not all jazz pianists leave out the root when they play voicings: Bud Powell, one of the best-known of the bebop pianists, and Horace Silver, whose quintet included many of jazz's biggest names from the 1950s to the 1970s, included the root note in their voicings.
[3][4] Improvising chord-playing musicians who omit the root and fifth are given the option to play other notes.
An experienced comping performer playing electric guitar or piano may add or remove notes as chosen according to the style and desired sound of that musician, but must do so in a way that still emphasizes the correct musical context for other musicians and listeners.
This provides an accurate and easily understandable basis for working out these chords in each key.
Note that this is not a complete list of compound intervals, only those that are commonly used in jazz chords.
These notes are not necessary to define the function of the chord, but are included to add colour or fill out the sound according to the tastes of the performer.
For instance, the dominant seventh ♯11 or Lydian dominant, C7♯11, comprises the notes: Basing this chord on the pitch, C, results in the pitches: The same chord type may also be voiced: This voicing omits both the root and the perfect fifth (G) and raises the major ninth (D) by an octave.
Often melody notes or other pitches influence an improviser's choice of chord types.
For example, if the melody note is the root of the chord, including a major seventh can cause dissonance.
The term basic can be used to describe dominant chords based on the major scale.
For expediency, musicians may use the abbreviation "alt"—as in C7alt—to describe the family of dominant chords with altered tones (including the ♭5, ♯5, ♭9, ♯9, ♯11, or ♭13).
By altering it with a diminished fifth (♭5) or augmented fifth (♯5), extra tension and dissonance is added, which strengthens the resolution to the I chord.