It is well-known that tone variation occurs in read speech due to a number of different contextual effects, most prominently local tone sequencing and downstepping, whereas in spontaneous speech, a greater variability of tone shape has been observed as arising from global discourse context. In this paper we show comparative results on tonal realization in read and spontaneous speech. Specifically, our study confirms the effects of tonal sequencing, and shows that higher amplitude increases conformity to lexical shape in both speech modes, while spontaneous speech is both more varied and pitch reduced in the defined f0 direction.
Bibliographic reference. Yang, Li-chiung (2011): "Tonal variations in Mandarin: new evidence from spontaneous and read speech", In INTERSPEECH-2011, 1397-1400.