 The focus on instrumental music remains relatively unchallenged over the course of the twentieth century, but new problems emerge. Phenomenological and analytic approaches explore the ontological nature of the musical work (see  §2.1  and  §2.6).  The philosopher and sociologist Theodor W. Adorno tackles the relationship between music’s emergence as an autonomous art and its possible role as an instrument of social critique (see  §2.5).