1. A method for use with a system including a first document containing at least some information in common with a spoken audio stream, the method performed by at least one computer processor executing computer program instructions to perform steps of: (A) identifying text in the first document, wherein the text represents a concept; (B) identifying, based on the identified text and a repository of finite state grammars, a plurality of spoken forms of the concept, including at least one spoken form not contained in the first document, wherein all of the plurality of spoken forms have the same content as each other; (C) replacing the identified text with a finite state grammar specifying the plurality of spoken forms of the concept to produce a second document; (D) generating a document-specific language model based on the second document, comprising generating at least some of the document-specific language model based on the finite state grammar; (E) using the document-specific language model in a speech recognition process to recognize the spoken audio stream and thereby to produce a third document; (F) filtering text from the third document by reference to the second document to produce a filtered document in which text filtered from the third document is marked as unreliable; and (G) using the filtered document and the spoken audio stream to train an acoustic model by performing steps of: (G)(1) applying a first speech recognition process to the spoken audio stream using a set of base acoustic models and a grammar network based on the filtered document to produce a first set of recognition structures; (G)(2) applying a second speech recognition process to the spoken audio stream using the set of base acoustic models and a second language model to produce a second set of recognition structures; and (G)(3) performing discriminative training of the acoustic model using the first set of recognition structures, the second set of recognition structures, the filtered document, and only those portions of the spoken audio stream corresponding to text not marked as unreliable in the filtered document.