8. An apparatus comprising: a microphone to receive speech; a processor; and a computer-readable medium storing instructions that when executed by the processor: buffer N audio frames of a plurality of audio frames associated with an audio signal, where N is greater than 1; pre-compute scores for a subset of context dependent models (CDMs); perform a graphical model search associated with the N audio frames; determine that a score of a context independent model (CIM) associated with a CDM and an audio frame is to be used in lieu of a score for the CDM when a score for the CDM is required by the graphical model search and the score for the CDM has not been pre-computed; pre-compute all scores of CIMs associated with the N frames; and store the pre-computed scores associated with the CIMs in a context independent score cache (CI-CACHE) wherein determining the CIM score associated with the CDM comprises retrieving a score from the CI-CACHE based on a CIM to CDM mapping table.
10. The apparatus of claim 8 , wherein performing the graphical model search comprises searching for one or more hidden Markov models.