Investigations of Issues for Using Multiple Acoustic Models to Improve Continuous Speech Recognition

This paper investigates two important issues in constructing and combining ensembles of acoustic models for reducing recognition errors. First, we investigate the applicability of the AnyBoost algorithm for acoustic model training. AnyBoost is a generalized Boosting method that allows the use of an arbitrary loss function as the training criterion to construct ensemble of classifiers. We choose the MCE discriminative objective function for our experiments. Initial test results on a real-world meeting recognition corpus show that AnyBoost is a competitive alternate to the standard AdaBoost algorithm. Second, we investigate ROVER-based combination, focusing on the technique for selecting correct hypothesized words from aligned WTN. We propose a neural network based insertion detection and word scoring scheme for this. Our approach consistently outperforms the current voting technique used by ROVER in the experiments.