The sentence recognition rate was evaluated for the text-closed experiments; the results are shown in Figure 3 . For comparison purposes, results for both the word bigram models and the word trigram models are also shown. In these experiments, the trigram and bigram values were smoothed by deleted-interpolation technique[8].
In Figure 3 , the vertical axis represents the sentence recognition rate while the horizontal axis represents the number of states. It shows the recognition rate for the 128-state Ergodic HMM is to be higher than that for the word bigram models. It also shows the recognition rate for the 256-state Ergodic HMM to be equal to that for the word trigram models. It is possible though that if the number of states were increased, the recognition rate would have exceeded that for the word trigram models.