Bass Pedal and Additional Chord Variations
If one bass note is repeated while the chords over that bass note are changing, then this effect is referred as a "Bass pedal". For example, Bb/C, Ab/C, G/C.
Example 72 uses various major chords over the same bass note → Bass pedal C.
So far the interval of the major seventh has only been used in conjunction with the major chord, however the major seventh is occasionally used in combination with the other three basic chords which adds an interesting color to the sound.
Another frequently used sound variation is combining a chord over a single bass note which may or may not be part of the actual chord itself, e.g., C/B. In this example the bass note could be seen as part of the chord even if it is not indicated in the chord itself.
The B note is the major seventh of the C major scale and when written as C/B, it is referred as the 3rd inversion of the Cmaj7 chord (see Major Seventh Inversions). Another example where the bass note is not part of the chord would be Db/C.
Remember that the most important thing for a bass player to do in a situation such as the previous example, is to play the note under the slash regardless of whether the actual note is part of the chord or not.
