What is Atonal Music ? Music Theory in a Nutshell The atonal system was a large break from the traditions of before. Western music first began with simple intervals in the time of Pythagorus . This system marked intervals like a unison and an octave as the most tonal and pleasing to the ear. In the middle ages, musicians used church modes . Monks even attributed certain religious qualities to specific music intervals like the fourth. In the Baroque Era , composers began to use what is now considered major and minor scales which escalated into the mathematical perfection or Mozart . True Western harmony was born. The 20th century saw a break from traditional Western harmony. When Arnold Schoenberg experimented with atonality, he developed a complex musical and mathematical system. Essentially, a composer would arrange the twelve notes of a scale in a specific row, and then compose using those rows (in that order alone) to eliminate any sense of tonality. Eventually composers b...