Highest Note — The Emotional Peak
The highest note in a phrase is the melodic climax — the moment with the most singability and emotional visibility. Whatever zone it occupies becomes the dominant mood of the entire phrase, even if it's brief.
Rule: The highest note should be placed deliberately, not accidentally. If your phrase climbs to FA without intention, it creates Zone 4 tension that may not serve the section. If you want a euphoric chorus peak, aim your highest note at DO or MI as a chord tone — Zone 1 at the apex creates a triumphant feeling.