Final answer:
Looping is used in a song's vocal melody to create repetition and enhance the overall musical experience.
Step-by-step explanation:
Looping is commonly used in a song's vocal melody to create repetition and enhance the overall musical experience. It involves taking a section or phrase of the melody and repeating it multiple times throughout the song. This technique can add a sense of familiarity and catchiness to the melody, making it easier for listeners to remember and sing along to. For example, in the song 'Happy' by Pharrell Williams, the vocal melody features a looped phrase that repeats throughout the chorus: 'Because I'm happy'.