*We follow the procedure reported in (Lee and Glass, 2012) to set up the HMM prior θ 0 .
the performance of the recognizers is evaluated and compared against three baselines: first, a graphemebased speech recognizer; second, a recognizer built by using an expert-crafted lexicon, which is referred to as an expert lexicon in the rest of the paper for simplicity; and third, a recognizer built by discovering the phonetic units and L2S pronunciation rules sequentially without using a lexicon.