Missing Data Solutions for Robust Speech Recognition

Current automatic speech recognisers rely for a great deal on statistical models learned from training data. When they are deployed in conditions that differ from those observed in the training data, the generative models are unable to explain the incoming data and poor accuracy results. A very noticeable effect is deterioration due to background noise. In the MIDAS project, the state-of-the-art in noise robustness was advanced on two fronts, both making use of the missing data approach. First, novel sparse exemplar-based representations of speech were proposed. Compressed sensing techniques were used to impute noise-corrupted data from exemplars. Second, a missing data approach was adopted in the context of a large vocabulary speech recogniser, resulting in increased robustness at high noise levels without compromising on accuracy at low noise levels. The performance of the missing data recogniser was compared with that of the Nuance VOCON-3200 recogniser in a variety of noise conditions observed in field data.