3. The method of claim 1 , wherein the dialog act clustering is performed using a non-parametric Bayesian hidden Markov model, under conditions that the dialog act is a hidden state and words included in the spoken sentences are observation values.
3. The method of claim 1 , wherein the dialog act clustering is performed using a non-parametric Bayesian hidden Markov model, under conditions that the dialog act is a hidden state and words included in the spoken sentences are observation values. 7. The method of claim 3 , wherein the dialog act clustering finally infers the dialog act using Gibbs sampling.