CONFIDENCE ESTIMATION BASED ON FREQUENCY

Devices, systems and methods are disclosed for estimating a prior probability for speech recognition by taking into account a number of observations of a particular word and a prior probability for a group of words having a similar number of observations. For example, a prior probability may be determined by combining a number of correct results and a number of observations for a group of words and calculating a prior probability of the entire group. Further, a prior probability may be determined for a word that was not previously observed by determining a prior probability for a group of words that have been observed once. The prior probability for a particular word may be determined differently as the number of observations increases and may transition from the group prior probability to an individual prior probability when the number of observations exceeds a threshold.