I think that you might be confused.
The
Speech SDK (tutorial)[
^] and WPF are entirely different things.
Use the Speech SDK for the speechy bits and WPF, Windows Forms, a Web App or ASP.Net for the showy bits.
[After OPs comment]
Even this[
^] uses WPF for
Presentation, and that's what WPF is (Windows
Presentation Framework) and the Speech SDK for the speech parts.
Everyone seems to think that WPF is some sort of miracle but it isn't. It is just another (admittedly more controllable) way of showing the 'standard' Windows UI.
[/After OPs comment]