I am not a musician. However, when I hear music, I can identify the melody; it is what I hum to myself afterward. If I am very familiar with the piece I may hear the layers of orchestration that give the music weight. In a long piece of music such as a symphony, I can hear the theme reappear in the variations throughout the movements. I also know when one piece of music is over and another begins. This begins to qualify me to see themes and variations in landscapes.