Comparing a data-driven and a rule-based approach to predicting prosodic features of German. Tagungsband der 12. Konferenz Elektronische Sprachsignalverarbeitung

The perceived quality of synthetic speech strongly depends on its prosodic naturalness. Departing from works by Mixdorff on a linguistically motivated model of German intonation based on the Fujisaki model, the current paper presents a perceptual comparison between a rule-based sequential and a data-driven integrated model of prosody. The experiment comprised resynthesis and diphone synthesis stimuli produced with prosodic features predicted by the two models. In addition, a number of reference stimuli from an earlier experiment were included which were produced by means of controlled prosodic degradation. Isolated sentences from two different corpora served as speech material. Results show that the integrated model outperforms the rule-based model in terms of the accuracy of phone durations predicted. In terms of the F0 contour generation, however, the integrated model is not rated better. Furthermore, these findings are only significant in the case of resynthesis stimuli whereas diphone synthesis stimuli are judged generally as being of poor quality, irrespective of the prosodic model. This fact clearly speaks against testing diphone synthesis samples against resynthesis in the same evaluation, as the segmental quality overrules the prosodic quality. 1