Why can music suddenly change our emotions?

Answer 1

The reason is that emotions are associated with sound and other senses on the right side of the brain. This is the "logic" of the RIGHT side cortex, to make these associations. These associations are personally meaningful, identify familiar patterns for us, so help us make our way through life.

So music can quite easily and naturally trigger certain emotions. It's one of the things the right side of the brain does.

The "language" of music is a lot different from our spoken and written language of communication, which organizes the LEFT side of the brain, which forms the foundations of rational thought and analytical reasoning.

Both sides of the brain operate simultaneously and even communicate with each other.