The contribution of phonation type to the perception of vocal emotions in German: an articulatory synthesis study

Vocal emotions are signaled by specific patterns of prosodic parameters, most notably pitch, phone duration, intensity, and phonation type. Phonation type was so far the least accessible parameter in emotion research, because it was difficult to extract from speech signals and difficult to manipulate in natural or synthetic speech. The present study built on recent advances in articulatory speech synthesis to exclusively control phonation type in re-synthesized German sentences spoken with seven different emotions. The goal was to find out to what extent the sole change of phonation type affects the perception of these emotions. Therefore, portrayed emotional utterances were re-synthesized with their original phonation type, as well as with each purely breathy, modal, and pressed phonation, and then rated by listeners with respect to the perceived emotions. Highly significant effects of phonation type on the recognition rates of the original emotions were found, except for disgust. While fear, anger, and the neutral emotion require specific phonation types for correct perception, sadness, happiness, boredom, and disgust primarily rely on other prosodic parameters. These results can help to improve the expression of emotions in synthesized speech and facilitate the robust automatic recognition of vocal emotions.