Résumé : Objective: To examine the mechanisms responsible for the reduction of the mismatch negativity (MMN) ERP component observed in response to pitch changes when the soundtrack of a movie is presented while recording the MMN. Methods: In three experiments we measured the MMN to tones that differed in pitch from a repeated standard tone presented with a silent subtitled movie, with the soundtrack played forward or backward, or with soundtracks set at different intensity levels. Results: MMN amplitude was reduced when the soundtrack was presented either forward or backward compared to the silent subtitled movie. With the soundtrack, MMN amplitude increased proportionally to the increments in the sound-to-noise intensity ratio. Conclusion: MMN was reduced in amplitude but had normal morphology with a concurrent soundtrack, most likely because of basic acoustical interference from the soundtrack with MMN-critical tones rather than from attentional effects. Significance: A normal MMN can be recorded with a concurrent movie soundtrack, but signal amplitudes need to be set with caution to ensure a sufficiently high sound-to-noise ratio between MMN stimuli and the soundtrack. © 2013 International Federation of Clinical Neurophysiology.