Natural speech is highly complex and variable. Spoken language, in contrast to written language, does not have any clear word boundaries. Adult listeners can exploit different types of information to segment the continuous stream such as acoustic and semantic information. However, the weight of these cues, when co-occurring, remains to be determined. Behavioural tasks are not conclusive on this point as they focus participants' attention on certain sources of information, thus biasing the results. Here we looked at the processing of homophonic utterances such as "l'amie" vs "la mie" (both /lami/) which include fine acoustic differences and for which the meaning changes depending on segmentation. To examine the perceptual resolution of such ambiguities when semantic information is available, we measured the online processing of sentences containing such sequences in an ERP experiment involving no active task. In a congruent context, semantic information matched the acoustic signal of the word "amie". However, in the incongruent condition, the semantic information carried by the sentence and the acoustic signal were leading to different lexical candidates. Our results suggest a preponderant weight of semantic information that takes over the acoustic information.