  Imbuing machines with the ability to talk has been a longtime pursuit of
artificial intelligence (AI) research. From the very beginning, the community
has not only aimed to synthesise high-fidelity speech that accurately conveys
the semantic meaning of an utterance, but also to colour it with inflections
that cover the same range of affective expressions that humans are capable of.
After many years of research, it appears that we are on the cusp of achieving
this when it comes to single, isolated utterances. This unveils an abundance of
potential avenues to explore when it comes to combining these single utterances
with the aim of synthesising more complex, longer-term behaviours. In the
present chapter, we outline the methodological advances that brought us so far
and sketch out the ongoing efforts to reach that coveted next level of
artificial expressivity. We also discuss the societal implications coupled with
rapidly advancing expressive speech synthesis (ESS) technology and highlight
ways to mitigate those risks and ensure the alignment of ESS capabilities with
ethical norms.
