8. A system of keyword recognition in a speech signal, the system comprising: one or more processors configured to: sample the speech signal in one or more frames; determine a first likelihood score of one or more features of a frame, of the one or more frames, of the speech signal being associated with one or more states in a first model, wherein the one or more states in the first model correspond to one or more tied triphone states of a keyword to be recognized in the speech signal, and wherein the one or more features comprise a frequency of an audio in the frame; determine a second likelihood score of the one or more features of the frame of the speech signal being associated with one or more states in a second model, wherein the one or more states in the second model correspond to one or more monophone states of the keyword to be recognized in the speech signal; determine a third likelihood score based on the first likelihood score and the second likelihood score, wherein the third likelihood score is deterministic of a likelihood of the frame corresponding to keywords other than the keyword; and determine a presence of the keyword in the speech signal based on the first likelihood score and the third likelihood score.
12. The system of claim 8 , wherein the one or more processors are further configured to determine a first score for each of the one or more states in the first model based on the first score of the one or more states in the first model for a previous frame, of the one or more frames, of the speech signal and the first likelihood score, wherein the keyword is recognized in the speech signal based on the first score.