Understanding Basic Music Theory - Catherine Schmidt-Jones [66]
Note
All added notes and extensions, including sevenths, introduce dissonance into the chord. In some modern music, many of these dissonances are heard as pleasant or interesting or jazzy and don't need to be resolved. However, in other styles of music, dissonances need to be resolved, and some chords may be altered to make the dissonance sound less harsh (for example, by leaving out the 3 in a chord with a 4).
You may have noticed that, once you pass the octave (8), you are repeating the scale. In other words, C2 and C9 both add a D, and C4 and C11 both add an F. It may seem that C4 and C11 should therefore be the same chords, but in practice these chords usually do sound different; for example, performers given a C4 chord will put the added note near the bass note and often use it as a temporary replacement for the third (the "3") of the chord. On the other hand, they will put the added note of a C11 at the top of the chord, far away from the bass note and piled up on top of all the other notes of the chord (including the third), which may include the 7 and 9 as well as the 11. The result is that the C11 - an extension - has a more diffuse, jazzy, or impressionistic sound. The C4, on the other hand, has a more intense, needs-to-be-resolved, classic suspension sound. In fact, 2, 4, and 9 chords are often labelled suspended (sus), and follow the same rules for resolution in popular music as they do in classical.
Figure 5.35.
Low-number added notes and high-number added notes are treated differently. So even though they both add an F, a C4 suspension will sound quite different from a C11 extended chord.
Bass Notes
The bass line of a piece of music is very important, and the composer/arranger often will want to specify what note should be the lowest-sounding in the chord. At the end of the chord name will be a slash followed by a note name, for example C/E. The note following the slash should be the bass note.
Figure 5.36. Naming the Bass Note
The note following the slash is the bass note of the chord. It can be a note that is already in the chord - making the chord a first or second inversion - or it can be an added note, following the same basic rules as other added notes (including using it to replace other notes in the chord).
The note named as the bass note can be a note normally found in the chord - for example, C/E or C/G - or it can be an added note - for example C/B or C/A. If the bass note is not named, it is best to use the tonic as the primary bass note.
Exercise 5.4.3. (Go to Solution)
Name the chords. (Hint: Look for suspensions, added notes, extensions, and basses that are not the root. Try to identify the main triad or root first.)
Figure 5.37.
Exercise 5.4.4. (Go to Solution)
For guitarists, pianists, and other chord players: Get some practical practice. Name some chords you don't have memorized (maybe F6, Am/G, Fsus4, BM7, etc.). Chords with fingerings that you don't know but with a sound that you would recognize work best for this exercise. Decide what notes must be in those chords, find a practical fingering for them, play the notes and see what they sound like.
Altering Notes and Chords
If a note in the chord is not in the major or minor scale of the root of the chord, it is an altered note and makes the chord an altered chord. The alteration - for example "flat five" or "sharp nine" - is listed in the chord symbol. Any number of alterations can be listed, making some chord symbols quite long. Alterations are not the same as accidentals. Remember, a chord symbol always names notes in the scale of the chord root, ignoring the key signature of the piece that the chord is in, so the alterations are from the scale of the chord, not from the key of the piece.
Figure 5.38. Altered Chords
There is some variation in the chord symbols for altered chords. Plus/minus or sharp/flat