The present paper investigated the event-related brain potential correlates of the processing of word stress related acoustic changes. We studied the processing of non-speech stimuli containing similar intensity and f0 changes as speech stimuli in a passive oddball paradigm. Contrary to our previous results using speech stimuli with a trochaic stress pattern contrasted with a iambic stress pattern, non-speech stimuli elicited a single MMN component. This result was interpreted as showing that the processing of stress information is based on speech specific mechanisms, instead of solely acoustic mechanisms.