1. A method for converting speech dictated by a user to text in a speech based document, the method comprising: associating a basic context with the speech based document, the basic context comprising a first lexicon and first language model; associating a first sub context, of the basic context, with a first portion of the speech based document, the sub context comprising a second lexicon and a second language model; recognizing speech corresponding to the first portion using the first sub context; and recognizing speech corresponding to portions of the electronic document to which no sub context has been associated using the basic context.