A review article that makes some useful connections between HMM-based speech synthesis and unit selection.
Heiga Zen, Alan Black and Keiichi Tokuda “Statistical parametric speech synthesis” Speech Communication
Volume 51, Issue 11, November 2009, Pages 1039–1064 DOI: 10.1016/j.specom.2009.04.004
Publisher’s version (preferred)
Publisher’s version (preferred for Edinburgh University students)
Author’s version (only use as a last resort)