1. A method of speech recognition processing comprising: in an automatic speech recognition engine: producing with a pattern matching recognizer an N-best list of recognition hypotheses corresponding to a spoken input; and rescoring the hypotheses in the automatic speech recognition engine to produce a rescored N-best list output from the automatic speech recognition engine; wherein the rescoring uses a plurality of rescoring categories based on position in the rescored N-best list such that some positions in the rescored N-best list are rescored based on a first combination of rescoring categories and other positions in the rescored N-best list are rescored based on a second combination of rescoring categories.