Strange behaviour with voices from Voxin

[Linux for blind general discussion]

Hi,

today I bought the Anna voice for the German language from Voxin / 
Oralux. I can change voice settings in orca, set the speech rate, pitch 
and so on and everything seems to work fine. But after a few minutes, or 
after a specific action, I do not yet know, the pitch of the voice is 
getting higher and higher and stays at this level. Also switching speech 
back to espeak-ng and back to Voxin Anna the pitch does not get back to 
the normal level I've configured.


Is someone also using voices from Voxin and is this behaviour known or 
is this related to the German Anna voice?

Cheers,

   Schoepp