Speech recognizing apparatus having optimal phoneme series comparing unit and speech recognizing method

Abstract

A recognizing target vocabulary comparing unit calculates a compared likelihood of recognizing target vocabulary, i.e., a compared likelihood of registered vocabulary, by using the time series of the amount of characteristics of an input speech. An environment adaptive noise model comparing unit obtains a likelihood that respective recognizing-unit standard patterns coincide with a time series of the amount of characteristics representing the characteristics of the input speed. A first rejection unit determines whether or not the input signal is noise, on the basis of a likelihood of coincidence obtained by the recognizing target vocabulary comparing unit, and a second rejection determining unit determines whether or not the input signal determined to be noise by the first rejection determining unit is noise, on the basis of the likelihood of coincidence obtained by the recognizing target vocabulary comparing unit and the likelihood of coincidence obtained by the environment adaptive noise model comparing unit. An optimal phoneme series comparing unit determines a likelihood that respective recognizing-unit standard patterns coincide with the time series of the amount of characteristics. When the first or second rejection determining unit determines the input signal to be noise, the environment adaptive recognizing unit selecting unit adaptively updates an order of selection of the recognizing-unit standard pattern on the basis of the likelihood of coincidence obtained by the optimal phoneme series comparing unit. Thus, the environment adaptive noise model matches to a real environment and the rejection determination can be performed for a noise input with high accuracy.