ABSTRACT Recent studies show that task-irrelevant speech affects subsequent behaviour. For instance, category-exemplar production is primed if those exemplars were previously auditory distractors that accompanied the presentation of visual digits for serial recall (Röer et al., 2017. Semantic priming by irrelevant speech. Psychonomic Bulletin & Review, 24(4), 1205–1210. https://doi.org/10.3758/s13423-016-1186-3). This study examines semantic organisation as a boundary condition for the semantic priming effect. In a between-participants design, sequences of auditory distractors were either semantically organised (eight exemplars from one category) or random (one exemplar from each of eight categories). Semantic priming was measured by comparing production probability of previously encountered words against a matched unencountered set. Prior research indicates that an unexpected categorical change in task-irrelevant speech disrupts performance, suggesting processing of shared categorical membership enhances semantic priming (e.g. Vachon et al., 2020. The automaticity of semantic processing revisited: Auditory distraction by a categorical deviation. Journal of Experimental Psychology: General, 149(7), 1360–1397. https://doi.org/10.1037/xge000071). Consistent with these findings, semantic priming was found when distractor words were semantically organised but was absent with randomly presented exemplars, offering insight into the semantic processing of background sound.