About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
INTERSPEECH 2009
Conference paper
Towards using hybrid word and fragment units for vocabulary independent LVCSR systems
Abstract
This paper presents the advantages of augmenting a word-based system with sub-word units as a step towards building open vocabulary speech recognition systems. We show that a hybrid system which combines words and data-driven, variable length sub word units has a better phone accuracy than word only systems. In addition the hybrid system is better in detecting Out-Of-Vocabulary (OOV) terms and representing them phonetically. Results are presented on the RT-04 broadcast news and MIT Lecture data sets. An FSM-based approach to recover OOV words from the hybrid lattices is also presented. At an OOV rate of 2.5% on RT-04 we observed a 8% relative improvement in phone error rate (PER), 7.3% relative improvement in oracle PER and 7% relative improvement in WER after recovering the OOV terms. A significant reduction of 33% relative in PER is seen in the OOV regions. Copyright © 2009 ISCA.