Synthesised stimuli were used to investigate how two notionally\nseparable dimensions of tone-of-voice? voice quality and\nfundamental frequency? are involved in the expression of\naffect. Listeners were presented with three series of stimuli:\n(1) stimuli exemplifying different voice qualities, (2) stimuli\nall with modal voice quality but with different affect-related f0\ncontours, and (3) stimuli incorporating variation in both voice\nquality and affect-related f0 contours. A total of 15 stimuli\nwere rated for 12 different affective attributes. Voice quality\ndifferentiation appears to account for the highest affect ratings\noverall, as indicated by the scores obtained for stimuli series\n(1) and (3). The relatively weaker affect signalling of stimuli\ndifferentiated by f0 alone corroborates findings in [2]. It also\nsuggests that for the generation of expressive, affectively\ncoloured speech synthesis, it is not sufficient to manipulate\nonly f0; we also need to capture the voice quality dimension\nof the voice source.