1. A method for recognizing speech in a speech recognition system comprising the steps of: receiving input speech from a user in a speech dialog where there is at least one point in the speech dialog where there is a grammar of possible responses and at least one expected response, the at least one expected response being a subset of the grammar and known to be the at least one expected response in the speech recognition system before receiving the user input speech, the at least one expected response including the most likely response or responses expected to be uttered by the user at the at least one point in the speech dialog and having a model associated therewith; generating acoustic features of the input speech; directly comparing the input speech acoustic features only to the model that is associated with the at least one expected response, rather than to models associated with additional possible responses, to generate an associated confidence factor; comparing the confidence factor to an acceptance threshold for accepting the expected response as the result of the speech recognition.