Shigenobu Seto

Speech dialogue system for facilitating improved human-computer interaction

A speech dialogue system capable of realizing natural and smooth dialogue between the system and a human user, and easy maneuverability of the system. In the system, a semantic content of input speech from a user is understood and a semantic content determination of a response output is made according to the understood semantic content of the input speech. Then, a speech response and a visual response according to the determined response output are generated and outputted to the user. The dialogue between the system and the user is managed by controlling transitions between user states during which the input speech is to be entered and system states during which the system response is to be outputted. The understanding of a semantic content of input speech from a user is made by detecting keywords in the input speech, with the keywords to be detected in the input speech limited in advance, according to a state of a dialogue between the user and the system.

A scheme for pitch extraction of speech using autocorrelation function with frame length proportional to the time lag

Although pitch extraction schemes based on the short-time autocorrelation function offer reliable results for most of the speech signal, the autocorrelation peaks indicating fundamental period fluctuate with frame position, causing occasional pitch extraction errors. In order to reduce these errors, a scheme using a new definition of normalized short-time autocorrelation function is proposed. One of the major advantages of the definition over conventional ones is that the frame length changes in proportion to the time lag, and, therefore, the input speech can be analyzed without any knowledge of the fundamental frequency range of the speaker. Two methods are proposed for the normalization, and the one compensating for variations of the short-time power of the waveform is shown to offer better results. A system for pitch extraction is constructed on a workstation, and the validity of the proposed scheme is demonstrated by experiments using the connected speech of male and female announcers.<<ETX>>

Spontaneous speech dialogue system TOSBURG II and its evaluation

Abstract We have developed a spontaneous speech dialogue system TOSBURG II, employing keyword-based spontaneous speech understanding and multimodal response generation, with adaptive speech response cancellation. Since in multimodal interaction, the user understands the systems response by a visual output before its speech response is completed, the user often interrupts the systems speech response. Therefore, our adaptive speech response cancellation serves to facilitate natural human-computer interaction by allowing the users interruption. We have also developed an evaluation environment for dialogue data collection and the performance of TOSBURG II. Unlike conventional data collection systems, TOSBURG II collects in this environment not only speech data and the final results of speech understanding but also its intermediate results as dialogue data, to use them for the evaluation and improvement of the system. The results of our dialogue experiments using TOSBURG II prove the effectiveness of adaptive speech response cancellation for natural interaction, confirming that the dialogue data and the evaluation environment will contribute to a further development of spontaneous speech dialogue systems.