To transcribe speech, automatic speech recognition systems use statistical methods, particularly hidden Markov model and N-gram models. Although these techniques perform well and lead to efficient systems, they approach their maximum possibilities. It seems thus necessary, in order to outperform current results, to use additional information, especially bound to language. However, introducing such knowledge must be realized taking into account specificities of spoken language (hesitations for example) and being robust to possible misrecognized words. This document presents a state of the art of these researches, evaluating the impact of the insertion of linguistic information on the quality of the transcription.