Prosodic manipulation system of speech material for perceptual experiments

In perceptual experiments, quantitative manipulation of acoustic features in speech material is often required. And obviously, it can be realized only with speech synthesis techniques. Some of the authors have conducted a series of perceptual experiments, through which they have realised the necessity of a system to generate more natural speech. With these backgrounds, a speech stimuli generation system was developed using an analysis resynthesis technique, where users can freely manipulate prosodic features of input speech and the manipulated material is obtained as synthetic speech. Degree of resemblance to human speech (henceforth, RHS degree) of the synthesized material was investigated in evaluation experiments. As a result, no perceptual difference was found between synthesized sentences with wrong accents and spoken sentences with the same wrong accents. Furthermore, RHS degree of synthesized sentences with correct accents exceeded that of spoken sentences with flat F0 contours. These results clearly indicate that this system is useful for the preparation of speech stimuli in perceptual experiments