Two experiments were conducted to examine how people arrive at stimulus-specific prospective metacognitive judgments of distraction by music. According to the direct-access account, people have a direct access to the processes underlying distraction, for example, to the degree that different types of sounds capture their attention. According to the processing-fluency account, people rely on the processing-fluency heuristic to make judgments about the distracting effects of music. To test these competing accounts against each other, we manipulated the playback direction of music in two experiments by playing piano melodies in forward or backward direction. Replicating previous findings, forward and backward music disrupted serial recall to the same degree. However, subjective fluency ratings showed that forward music was perceived to be more fluently processed than backward music. Stimulus-specific prospective metacognitive judgments showed that only backward music was judged to be distracting, whereas forward music was not ascribed a distracting effect in comparison to quiet. These results support the processing-fluency account and contradict the direct-access account.