1. A computer-implemented method of a voice server for producing user-specific interpretations of user utterances, the method comprising: accessing, by the voice server, a literal speech recognition corpus comprising a plurality of expressions; accessing, by the voice server, a concept tagging module for identifying instances of a plurality of concepts within an expression; generating, by the voice server, a parameterized speech recognition corpus by applying the concept tagging module to the expressions of the literal speech recognition model corpus in order to identify, within the expressions, portions of the expressions that are instances of the concepts; generating, by the voice server, a parameterized statistical model based on the parameterized speech recognition model corpus, the parameterized statistical model indicating a plurality of probability scores for a corresponding plurality of n-grams, some of the plurality of n-grams including a placeholder indicating one of the plurality of concepts; accessing, by the voice server, a plurality of language sub-models corresponding to the plurality of concepts, at least some of the plurality of language sub-models being customized for a user; receiving, by the voice server over a computer network, an utterance of the user, the utterance having been accepted from the user at a client device as spoken input; and generating, by the voice server, a user-specific interpretation of the utterance using both the parameterized statistical model and ones of the plurality of language sub-models corresponding to instances of the concepts in the utterance, the interpretation comprising a sequence of recognized words.