A very simple, and very efficient LPC diphone synthesizer using the "donovan" diphones is also supported. This synthesis method is primarily the work of Steve Isard and later Alistair Conkie. The synthesis quality is not as good as the residual excited LPC diphone synthesizer but has the advantage of being much smaller. The donovan diphone database is under 800k.
The diphones are loaded through the Donovan_Init function
which takes the name of the dictionary file and the diphone file
as arguments, see the following for details
lib/voices/english/don_diphone/festvox/don_diphone.scm