Intro / Verse 1
Zone 1–2. Establish the key with stable chord tones. Leave openness for growth — don't peak too early. Keep a question in the phrase.
Pre-Chorus
Shift toward Zone 2–3. Unstable notes and non-chord tones build expectation. The ear should be leaning forward into the chorus.
Bridge
Zone 3–4 territory. Maximum contrast. Explore FA, TI as non-chord tones. This is the emotional climax — the furthest from home the song travels.
Chorus
Land in Zone 1. The contrast with pre-chorus creates the "payoff" feeling. The hook note should be a stable chord tone — Zone 1 at the peak.
Verse 2 / Post-Ch
Similar to Verse 1 but can tolerate slightly more tension — the listener knows the story now and can handle more complexity before the chorus.
Final Chorus / Outro
Return to Zone 1. After bridge tension, the final chorus resolution feels cathartic. Outro descends gradually toward DO — let the listener land in peace.