1. A method for automatically adjusting operation of a speech recognition system comprising: revising operation of the speech recognition system so as to change an associated receiver operating characteristic (ROC) curve describing performance of the speech recognition system with respect to rates of false acceptance (FA) versus correct acceptance (CA); and automatically adjusting a confidence scoring functionality related to recognition reliability for a given input utterance such that where the ROC curve is better for a given operating point after revising the operation of the speech recognition system, the adjusting reflects a double gain constraint to maintain FA and CA rates at least as good as before revising operation of the speech recognition system.