On the influence of frame-asynchronous grammar scoring in a CSR system

It is usually assumed that grammar probabilities and acoustic probabilities in a continuous speech recognition system have to be incorporated to the general score with different weights. This is an experimental fact and there is no generally accepted theoretical explanation. We propose an explanation to this fact, related to the way grammar scoring is incorporated in the searching procedure. Accordingly to this explanation, we perform a set of experiments to test our hypothesis. We are also proposing a new way of introducing grammar probabilities in a tree-based vocabulary search strategy, where systems are usually bound to use the worst strategy. To apply our ideas to unigrams is rather simple. For more complex language models like bigrams we have to implement a new procedure.