近畿方言2拍単語アクセント型の分析及び知覚

抄録

For the purpose of elucidating the relationship between the word accent types and the contours of fundamental frequency (F_0-contour), a model has been presented by one of the authors for the process of generating an F_0-contour from "voicing" and "accent" commands, and has been applied to analyze the F_0-contours of word accent types in the Tokyo dialect. The present study was conducted to test the model's validity for the Kinki dialect, which posesses peculiar accent types not found in the Tokyo dialect (Table 1), and also to examine the perceptual significance of parameters of the model. The speech materials were the utterances of two-mora [ame] pronounced in all four accent types of the Osaka dialect (Table 2) by a male informant. Extraction of F_0-contours (Fig. 1) and their parameters were conducted with a digital computer. Using a functional model for generating the F_0-contour(Figs. 2 and 3), parameters were extracted from six utterances each of the accent types, by finding the best match between the observed and generated F_0-contours (Table 3). The close agreement between the observed and generated contours proved the model's validity for the Kinki dialect (Fig. 4). While the magnitude and rate of responses to voicing and accent command are considered to characterize the laryngeal functions of a speaker, the timing parameters of the accent command, i. e. the onset and the end, are found to be specific to each accent type, and can clearly separate the four accent types (Fig. 5). The perceptual relevance of these timing parameters was examined by the identifications tests of accent types using 40 synthetic speech stimuli consisting of both typical stimuli of the four accent types and intermediate stimuli, generated by systematicallyvarying the timing parameters of the accent command. The subjects were 10 speakers of the Osaka dialect and two speakers of the Tokyo dialect. The perceptual boundary between two accent types was determined for each subject (Fig. 6), which was quite clear-cut and almost agreed in all the subjects (Fig. 7), indicating the perceptual importance of these timing parameters in the identification of accent types. Further experiments using stimuli with systematic shifts in the timing of formant frequency patterns indicated that the relative timing of the accent command and the segmental features of a particular phoneme is quite important for the identification of a specific accent type (Figs. 8 and 9), but not necessarily for other types. These results indicate that the perception of word accent requires specification of certain features for temporal units which are smaller than mora, which is commonly accepted as the suprasegmental unit of spoken Japanese.