旋律 (xuánlǜ) is the general word for 'melody' — a sequence of notes that forms a tune. It's broader than 调 (diào), which often refers to a specific key or pitch in music, and 曲 (qǔ), which means a complete musical piece or song. 腔 (qiāng) is a specialized term for melody in Chinese opera or a regional accent in speech.