We report a dissociation of two forms of auditory distraction within a single repeated-measures experiment using a novel Stroop serial recall task in which participants were oriented either to serially recall six color-words (low task-load condition) or the incongruent colors in which those words were presented (high task-load condition). The disruption of serial recall due to a single deviation in the voice delivering a sequence of task-irrelevant speech tokens (the deviation effect) was replicated in the low task-load condition but eliminated in the high task-load condition. In contrast, the disruption of serial recall by continuously changing compared to a repeating sound (the changing-state effect) did not differ according to task-load. The results provide further support for a duplex-mechanism account of auditory distraction: Disruption due to attentional diversion (cf. the deviation effect) is modulated by levels of focal task-engagement whereas interference-by-process (cf. changing-state effect)—in which the processing of the sound conflicts with seriation processes involved in task performance—is not.