Why 감사합니다 sounds like 감사함니다

Sound rules shift letters at syllable boundaries: ㄱ + ㅎ → ㅋ (축하 → 추카), and final ㄷ/ㅅ/ㅆ all snap to [t] before a pause.

Liaison: a final consonant hops to an empty vowel slot. 한국어 sounds 한-구-거. 음악 sounds 유막 — trust your ears over your eyes.

You don't memorize these — you absorb them by reading aloud. But knowing they EXIST stops the 'wait, why?' spiral.