Speech recognition of broadcast news for the European Portuguese language

This paper describes our work on the development of a large vocabulary continuous speech recognition system applied to a broadcast news task for the European Portuguese language in the scope of the ALERT project. We start by presenting the baseline recogniser AUDIMUS, which was originally developed with a corpus of read newspaper text. This is a hybrid system that uses a combination of phone probabilities generated by several MLPs trained on distinct feature sets. The paper details the modifications introduced in this system, namely in the development of a new language model, the vocabulary and pronunciation lexicon and the training on new data from the ALERT BN corpus currently available. The system trained with this BN corpus achieved 18.4% WER when tested with the F0 focus condition (studio, planed, native, clean), and 35.2% when tested in all focus conditions.