Here are some theories
Our brains love patterns; patterns help us understand the world, and music is a pattern. Research has shown that when we listen to music, our brain releases dopamine, making us feel happy. In one study published in the journal Nature Neuroscience, researchers found that dopamine release is strongest when a piece of music reaches an emotional peak. This may explain why we like music because it has such an effect on our feelings. But this still does not explain why we feel such sympathy in the first place. Normally, our brains release dopamine during survival behaviors as an adaptation that encourages us to do more of those behaviors. But music doesn't have the same meaning. One possibility is that it serves as a function of our love of patterns.
Most likely, we learned to recognize and appreciate patterns because it is an essential skill for survival. Does the rustling of trees mean that danger is lurking above us? Does the smell of smoke indicate that there might be a fire in my path and that I should run? When we listen, we always anticipate what harmonies, melodies, and rhythms might follow. This is why we usually don't like unfamiliar genres of music. When we are not familiar with a particular type of music, we have no basis for predicting its patterns. When we can't predict musical patterns, we quickly become bored. From our culture, we learn which sounds are music and the rest is just random noises.
Music can trick the brain
These explanations may explain why we experience joy from music but still do not reveal the full range of emotions that music can evoke. When we listen to a piece of music, its rhythm hooks us in a process called "entrainment." Passion forces us to gradually become synchronized with its rhythm. If the music is played at a fast tempo, our breathing and heart rate speed up by the rhythm. Our brain can then interpret this arousal as excitement. Research has shown that the more pleasant music we find, the higher our arousal level.
According to another theory, music affects areas of the brain that are tuned to speech, conveying all our emotions. “Our brains are particularly good at detecting emotion in speech,” says Aucouturier of the French Institute of Science. We want to understand whether people around us are happy, sad, afraid, or angry. Just as higher-pitched voices sound happier, so much of the information can be contained in one tone of a person's intonation. Music can then be a version of exaggerated speech. “No matter how happy my voice is, a piano, violin, or trumpet can make it 100 times happier,” says Aucouturier, because these instruments can create a wider range of notes than the human voice. We tend to reflect the emotions we hear in others; if the music imitates happy speech, the listener will become happy too."