In the converting form, click the "More Voices" button if it shows.
then it will show a voice list.
The voices in the list, can be from Speech One Core, or Speech Server (Microsoft Speech Platform - Version 11, support Windows 2003 Server or later, Windows 2008 Server or later).
Click "Add" button to add voices.
You need click "Yes" to add voices if there is a "Registry Editor" shows.