This is the catchy lab where we cook earworms that cling like glitter to a festival outfit. We blend craft with brain science so your chorus actually sticks. You will learn contour which is the shape of a melody, interval choice which means the distance between notes, and repetition patterns that feel addictive not annoying. We experiment with title placement, pre chorus timing, and those tail lines that punch the landing. Topline means the lead vocal melody and lyric riding the track. We show quick tests for memorability, crowd sing backs, and TikTok tryouts that validate early. Real life example. You sing the hook to three friends while making noodles. If they finish the second line without prompting, you keep it. If they blink at you, we iterate syllable count, stress, and lift. Hooks that convert.