Alternatively, it could recognize the broad class as a first pass, and then refine this into a full phonemic analysis for stressed syllables in a second pass, at the cost of multiplying passes through the speech data.
in order to match this to dictionary pronunciations, we train a confusion matrix on all realized/canonical phone pairs, to obtain P (dictionary phone|transcribed phone); these confusion probabilities are encoded as a finite state transducer C. C is derived by computing the strength of all correspondences between the phonetic transcription of what was actually said at the phone level and the canonical pronunciation of the corresponding words.