"I stayed inside the key and it still sounds wrong." This is almost always the cause: a note held a semitone above one of the chord's own notes.
Chapter 18 said any note in the key is usable. True, but where you put it and how long you hold it can still make a key note sound wrong. Let's remove that problem.
I used a note from the key and it sounds wrong. Why?
Because it sits a semitone above one of the notes in the chord currently sounding. A semitone is too close (chapter 26), so the two muddy each other — and the longer you hold it, the more obvious it gets.
The clash is a semitone above a chord tone.
Only the semitone above causes trouble
Cmaj7 is C, E, G and B. Add F and you have a note a semitone above E, so it fights with E. That is why a note from the same key can still muddy. Compare the three below.
- Cmaj7Cmaj7 alone (clean)
- Cmaj7 + FAdd F (a semitone above E — clashes)
- Cmaj7 + GAdd G (a chord tone — blends)
Only the second one sounds unsettled. F is not a bad note; it is simply colliding with the chord that happens to be sounding. The instant the chord changes to F, that same F becomes the most stable note available.
A scale note sitting a semitone above a note in the current chord. Held, it muddies — so avoid it or pass through quickly.
Where to watch out in the key of C
- Cmaj7 (I) — watch F. It sits a semitone above E.
- Em7 (iii) — watch F and C, a semitone above E and B respectively.
- G7 (V) — watch C. A semitone above B, and it weakens the dominant's pull.
- Am7 (vi) — watch F, a semitone above E.
- Dm7 (ii) — none. That is part of why ii is so easy to use, and why ii-V-I is everywhere.
How to fix a note that sounds wrong
- Suspect the long notes first. Short notes are rarely the problem.
- Count whether that note sits a semitone above a note in the current chord (chapter 26).
- If it does, move it to the nearest chord tone. A semitone or a whole tone is usually enough.
- If you really want that note, shorten it and move it to an off-beat.
Generate over a progression of sevenths and check whether the long notes are chord tones.
Generate over Cmaj7, Am7, Dm7, G7The clash is a semitone above a chord tone. Not forbidden — pass through it briefly on a weak beat and nobody notices.
Quick review
Everything here is answerable from this chapter. Pick an option and the answer appears straight away.
Question 1
Where does a clashing note sit relative to a chord tone?
Question 2
If you really want to use a clashing note?