Interspeech'2005 - Eurospeech
European Portuguese (EP) intonational contrast between statement and question contours was tested on a Categorical Perception based paradigm. From a natural sentence produced by a male speaker, a 15-step continuum was created, from declarative to question contour, through acoustic manipulation (PSOLA) and submitted to 20 EP listeners that performed two tasks: an identification and a discrimination task.
For identification test, subjects had to categorize each presented stimulus. In addition to response data, reaction times of the identification task were also collected. For the discrimination test, subjects were presented with an AX discrimination task and had to decide whether the stimuli in each pair were equal or different. Experimental design and procedures were developed with E-Prime.
Identification results confirmed that the contrast is indeed categorical. However, identification reaction-time measurements point to continuous rather than categorical perception. The absence of a consistent peak of discrimination in the cross-over between categories supports the continuous perception view.
Bibliographic reference. Falé, Isabel / Hub Faria, Isabel (2005): "Intonational contrasts in EP: a categorical perception approach", In INTERSPEECH-2005, 1705-1708.