The purpose of this research is to show that it is easier to identify the prosody of Algiers and Oran dialects when a focus is produced. For this study, we compared prosodic features associated with different types of focus: broad focus, emphatic narrow focus, contrastive narrow focus and interrogative focus. It appears from the acoustical analysis that recurrences of prosodic patterns that differentiate the two dialects were observed in narrow and interrogative focus. The analysis of the interaction between the identification of the two dialects and the four types of focus showed that Algiers and Oran speakers are better identified when their utterances are produced with narrow focus when it is placed at the edge of an intonation phrase and interrogative focus.