1. A speech recognition system implemented on a computer, the system comprising: a speech recognition engine comprising a plurality of modules for implementing a call flow having directed dialogs that a caller moves through during a call with the system, the speech recognition engine comprising a global module having defined therein primary concepts, and secondary concepts associated with the primary concepts, that are available to the caller throughout the call flow; a module configured to record a natural language audio input response from a caller; and a module configured to process at least a portion of the call flow and recognize one or more primary concepts and at least one secondary concept associated with each of the one or more primary concepts in an audio input comprising natural language, apply a score to each primary and secondary concept pair found in the audio input, and determine the caller response based on the concept pair with the highest score.