6. The information storage medium according to claim 1 , wherein the filler model generation section obtains a mean for defining probability density functions composing the Hidden Markov Model to be used as the filler model or its state based on a mean for defining one or a plurality of probability density functions classified into each of the clusters, and obtains a variance for defining probability density functions composing the Hidden Markov Model to be used as the filler model or its state based on a variance for defining one or a plurality of probability density functions classified into each of the clusters.
1. A computer-readable information storage medium that stores a program for generating Hidden Markov Models to be used for speech recognition with a given speech recognition system, the information storage medium storing a program that renders a computer to function as: a scheduled-to-be-used model group storage section that stores a scheduled-to-be-used model group including a plurality of Hidden Markov Models scheduled to be used by the given speech recognition system; and a filler model generation section that generates Hidden Markov Models to be used as filler models by the given speech recognition system based on all or at least a part of the Hidden Markov Model group in the scheduled-to-be-used model group; wherein the filler model generation section classifies a plurality of probability density functions composing all or at least a part of the Hidden Markov Model group in the scheduled-to-be-used model group into a plurality of clusters, obtains a given parameter for defining probability density functions composing Hidden Markov Models to be used as filler models, based on the obtained probability density functions of each of the clusters.