In my very short experience with speech syntetizers i get better results changing some letters for example:
"ola" for "hola" (means hello)
"ke" for "que"
The ñ souns near to "ni" "espania" for "españa" or like in catalan "espanya"

And be carefull because "ca" sounds "ka" and "ce" sounds "ze" so avoid the q and c and use only k and z

In spanish the b and the v have the sound of the b, so use only b.


Hope this helps.