This paper argues about pitch pattern variations of user utterances in human-machine dialogue. For intelligent humanmachine communication, it is essential that machines understand prosodic characteristics which imply a user's various attitude, emotion and intention beyond vocabulary. Our original focus is on particularly distinct pitch patterns and their roles in the actual dialogues. We used human-machine dialogues collected by a Wizard of OZ simulation, Many utterance segments belonged to

more »

... ters that were prosodically at patterns. From the result, we considered that utterances which belonged to the other clusters and those which were far from the centroids included non-verbal information. In these utterances, there were talks to themselves and questions to the machine including emotional expressions of a puzzle or a surprise. These pitch patterns were not only rich in ups and downs, but also their slopes were upward, while the pitch pattern were generally even or a little downward. These results indicate that peculiar pitch period patterns show non-verbal expressions. In order to actually utilize such information on human-machine interactions, the representative pitch patterns should be investigated concerning their relationship to various types of communication.