MusicReasonChords and Harmony
What happens if I add, omit, or alter a tone?
Start from a plain major triad and apply one explicit change: add a named extension, remove a stated tone, or alter an existing degree. This tool shows the before and after tone sets side by side; it never claims a tension is universally tasteful or that omitting a tone is always safe, since that depends on style and context this tool does not assume.
Answer
Understand
A "color tone" here means any explicit change to a chord's declared tone set: adding a named extension above the seventh, omitting a stated tone entirely, or altering an existing degree's pitch (raising or lowering it a semitone from its plain diatonic position). Every change is applied literally to the base chord's own tone list; the base chord's other tones stay exactly as spelled unless the change explicitly touches them.
Worked examples
Adding a 9th to a C major triad produces C, E, G, D; the third (E) is untouched, and the added D sits above the triad as a genuinely new fourth tone. Omitting the 3rd from that same C major triad produces C, G only, a bare fifth whose quality (major or minor) this tool then leaves undetermined rather than assuming. Altering the 5th toward a sharp-11 register respells that single tone in place, leaving root and third exactly where they were.
Method and limitations
The base chord's tones come from the same locked chord-formula vocabulary Chord Builder uses. An "add" change spells a new tone at the requested scale degree using the standard letter-name rule (degree 9 reuses the letter a step above the 2nd, degree 13 reuses the letter a step above the 6th) and appends it; an "omit" change simply removes any tone whose degree number matches; an "alter" change re-spells an existing degree's tone to a new semitone offset without changing which letter names are present. This tool does not rank changes by genre-appropriateness or voice-leading smoothness, both of which are style judgments outside its declared scope.
Adding a tension and altering a tension are deliberately kept as separate operations, since they answer different questions. Adding a 9th, 11th, or 13th introduces a genuinely new pitch above the chord's own seventh without touching any existing tone; altering an existing degree, such as raising a 5th toward a sharp-5 or sharp-11 register, respells a tone that was already present. Confusing the two would misrepresent what actually changed in the chord's own tone count, which this tool avoids by keeping each change type's effect on the tone list explicit and separately labeled in the result.