“Noise” is an important subject in sound studies research. However, due in large part to the fact that judgements about what constitutes noise are highly subjective, researchers have often struggled to define it. Where attempts have been made, many have settled on a definition of noise as “sound out of place,” a reformulation of Mary Douglas’ definition of “dirt” as “matter out of place” (Douglas 1966: 44). Beyond this, however, no effort has been directed towards exploring the link between dirt and noise or seeing how far the analogy between the two extends. This article corrects this omission by undertaking a close reading of Douglas’ writing on “dirt” and linking it to contemporary sound studies research. It argues that far more than simply giving rise to the definition “sound out of place,” Douglas’ classic anthropological work can be used as the basis for an integrated “theory of noise,” deepening our understanding of what it means when we describe a sound as “noise” and drawing attention to the ambiguous, transgressive and dangerous qualities and potentials of noise.