Segmental Conditional Random Fields and their Features – Geoffrey Zweig (Microsoft)
Segmental conditional random fields provide an exciting new approach to speech recognition based on the integration of numerous acoustic and linguistic cues. In this approach, acoustic detectors are applied to the audio signal, resulting in a stream of detection events. For example, phoneme, syllable or general acoustic-template detectors may be used. The detection streams are analyzed in word level segments, where long-span features are extracted. A log-linear model, in the form of a segmental conditional random field, integrates these acoustic features with language modeling features, to produce a probability distribution over word labels. The talkwill describe the theoretical background of this approach, a specific implementation in the form of a publically available toolkit, and results on both a voice search task, and the Wall Street Journal task. This is joint work with Patrick Nguyen.Seminar Video: Video of this lecture is available from the CLSP library upon request.
Geoffrey Zweig studied at the University of California at Berkeley earning a B.A. in physics (Summa Cum Laude) in 1985 and a PhD in computer science in 1998. After graduating he worked for eight years at the IBM TJ Watson research center, where he led the speech recognition efforts in the DARPA EARS and GALE programs and managed the Advanced Large Vocabulary Continuous Speech Recognition group. In 2006 he joined Microsoft Research in Redmond, WA as a Senior Researcher. His work at Microsoft has revolved around acoustic and language modeling techniques for voice search applications, and most recently in the development of the segmental CRF approach to ASR. He has published over 50 papers in the area of speech recognition along with numerous patents. In addition to Microsoft, he is on the affiliate faculty of the University of Washington. Dr. Zweig is a member of the ACM and senior member of the IEEE. He served from 2003 to 2006 as associate editor of the IEEE transactions on Audio Speech and Language Processing, and is currently on the editorial board of Computer Speech and Language. More about him can be found at http://research.microsoft.com/en-us/people/gzweig/