Unsupervised Lexicon Discovery from Acoustic Input Chia-ying Lee author Timothy J O’Donnell author James Glass author 2015 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal lee-etal-2015-unsupervised 10.1162/tacl_a_00146 https://aclanthology.org/Q15-1028/ 2015 3 389 403