QCRI advanced transcription system (QATS) for the Arabic Multi-Dialect Broadcast media recognition: MGB-2 challenge

In this paper, we describe Qatar Computing Research Institute's (QCRI) speech transcription system for the 2016 Dialectal Arabic Multi-Genre Broadcast (MGB-2) challenge. MGB-2 is a controlled evaluation using 1,200 hours audio with lightly supervised transcription Our system which was a combination of three purely sequence trained recognition systems, achieved the lowest WER of 14.2% among the nine participating teams. Key features of our transcription system are: purely sequence trained acoustic models using the recently introduced Lattice free Maximum Mutual Information (LF-MMI) modeling framework; Language model rescoring using a four-gram and Recurrent Neural Network with Max- Ent connections (RNNME) language models; and system combination using Minimum Bayes Risk (MBR) decoding criterion. The whole system is built using kaldi speech recognition toolkit.