1. A system comprising: a non-transitory, computer-readable media having computer-executable instructions stored thereon; and one or more hardware processors in communication with the non-transitory, computer-readable media that, having executed the computer-executable instructions are configured to: instantiate a feature extractor for extracting features of input speech signals and applying sequences of one or more labels to the extracted features; instantiate a non-optimized composed weighted speech transducer, the non-optimized composed weighted speech transducer being stored in the computer-readable media and being based on signals representing a hidden Markov model (HMM) transducer, a context dependent phone model, a lexicon model for pronunciation dictionary, and an N-gram language model for sentence probability; and instantiate a decoder for outputting decisions about the input speech signals based, at least in part, on the sequences of labels and the non-optimized composed weighted speech transducer.