humm, this is a good question. Music is a mix of sounds that form a melody, but this is not enough to be called music. May be is related with the feelings. People feels better with music that make them feel something: love, anger, happiness, something.
Althought, also is interesting see the level of complexity of the melodies for to be called good melodies. There are many melodies that are seen like good melodies not by the feelings that the get awake, but thye complexity of their rithms.
All is subjective after all....