update needed on software synthesizers for linux

[krishnakant Mane]

well, actually my main question is about the software synths available
under the gpl or lgpl.
I want to know if there are better synths than flite,  I want better
quality voices like IBM's viavoice or eloquence used by jaws for
windows.
or if there is a way we can use existing speach engines to generate
better voice.  I heard about festvox but is it for just adding new
voice with a diphone speach or can I improve the speaking quality like
inflection and the pronounciations etc.
if not then what are the better options.
thanks,
Krishnakant.