16. A system for performing key phrase detection comprising: a memory configured to store a start state based rejection model and a key phrase model associated with a predetermined key phrase; a digital signal processor coupled to the memory, the digital signal processor to update, at a current time instance, the start state based rejection model and the key phrase model based on scores of sub-phonetic units representative of received audio input, wherein the start state based rejection model includes a single rejection state having a plurality of rejection model self loops each associated with a particular score of the scores of sub-phonetic units, wherein the key phrase model includes a plurality of key phrase states interconnected by transitions therebetween, wherein the start state based rejection model and the key phrase model are connected by a first transition from the single rejection state to a first key phrase state of the plurality of key phrase states, and wherein to update the start state based rejection model and the key phrase model, the digital signal processor is to transition a score from a particular key phrase state of the plurality of key phrase states of the key phrase model to a next key phrase state of the plurality of key phrase states of the key phrase model, to transition the score from the particular key phrase state to the single rejection state of the start state based rejection model, and to generate a rejection likelihood score corresponding to the single rejection state of the start state based rejection model and a key phrase likelihood score corresponding to the key phrase model; and detect the predetermined key phrase in the received audio input based on the rejection likelihood score and the key phrase likelihood score; and provide a wake indicator or a command in response to the detected predetermined key phrase.
16. A system for performing key phrase detection comprising: a memory configured to store a start state based rejection model and a key phrase model associated with a predetermined key phrase; a digital signal processor coupled to the memory, the digital signal processor to update, at a current time instance, the start state based rejection model and the key phrase model based on scores of sub-phonetic units representative of received audio input, wherein the start state based rejection model includes a single rejection state having a plurality of rejection model self loops each associated with a particular score of the scores of sub-phonetic units, wherein the key phrase model includes a plurality of key phrase states interconnected by transitions therebetween, wherein the start state based rejection model and the key phrase model are connected by a first transition from the single rejection state to a first key phrase state of the plurality of key phrase states, and wherein to update the start state based rejection model and the key phrase model, the digital signal processor is to transition a score from a particular key phrase state of the plurality of key phrase states of the key phrase model to a next key phrase state of the plurality of key phrase states of the key phrase model, to transition the score from the particular key phrase state to the single rejection state of the start state based rejection model, and to generate a rejection likelihood score corresponding to the single rejection state of the start state based rejection model and a key phrase likelihood score corresponding to the key phrase model; and detect the predetermined key phrase in the received audio input based on the rejection likelihood score and the key phrase likelihood score; and provide a wake indicator or a command in response to the detected predetermined key phrase. 19. The system of claim 16 , wherein the plurality of key phrase states of the key phrase model are associated with second scores of the scores of sub-phonetic units, and wherein none of the second scores are included in the particular scores of sub-phonetic units associated with the rejection model self loops of the start state based rejection model.