Two experiments served to test the hypothesis that partially masking speech with pink noise (Experiment 1) or speech babble (Experiment 2) induces metacognitive illusions in judgments about the distracting effects of task-irrelevant speech on cognitive performance. Separate validation experiments have shown that masked speech is experienced as being disfluent relative to pure speech. If people rely on a (dis)fluency heuristic, masked speech should be predicted to be more distracting than pure speech. However, given that pink noise or speech babble mask the changes in the speech signal that drive auditory distraction, people should objectively be less distracted by masked speech than by pure speech in a serial-recall task. The results of both experiments support these hypotheses. Speech masked with pink noise or speech babble evoked a subjective experience of relative disfluency and both types of speech were predicted to be more distracting than pure speech. However, participants were objectively less distracted by masked speech than by pure speech. Even after multiple firsthand experiences of having ignored masked and pure speech during the serial-recall task, participants judged masked speech to have been more, not less, distracting than pure speech. Partially masking speech thus had opposite effects on judgments of distraction and objective distraction, providing evidence of pronounced metacognitive illusions in judgments of distraction.