1. A computer-implemented method for user dependent key phrase enrollment comprising: determining a sequence of most probable audio units corresponding to a received audio input representing a user defined key phrase, wherein each audio unit of most probable audio units corresponds to a frame of a plurality of frames of the audio input; processing the sequence of most probable audio units to eliminate at least one audio unit from the sequence of most probable audio units to generate a final sequence of audio units; and generating a key phrase recognition model representing the user defined key phrase based on the final sequence of audio units, the key phrase recognition model comprising a single rejection state having a transition to a key phrase model, wherein the key phrase model comprises a plurality of states having transitions therebetween, the plurality of states including a final state of the key phrase model, wherein the plurality of states of the key phrase model correspond to the final sequence of audio units.