In my earlier post about how to download and install SR languages for Vista, I somehow neglected to mention what languages are supported. Not surprisingly, we got some questions about this.
Q: What languages is Windows Speech Recognition available in?
A: For Speech Recognition, this info is available on the page on www.microsoft.com that talks about the feature: http://www.microsoft.com/windows/products/windowsvista/features/details/speechrecognition.mspx. It says "Windows Speech Recognition is available in English (U.S.), English (U.K.), German (Germany), French (France), Spanish (Spain), Japanese, Chinese (Traditional), and Chinese (Simplified)." It is not possible to extend this support in Vista. If you have a recognizer for another language, you can use it in other applications, but not in Windows Speech Recognition.
For TTS, Vista ships with US English and Chinese (Simplified) synthesizers. The Narrator screen reader (http://www.microsoft.com/windows/products/windowsvista/features/details/accessibility.mspx#narrator) does support other languages and other engines.
So, you might ask, why the difference? Well, Windows Speech Recognition includes lots of grammars that have to be localized into each language. Localizing the grammars is reasonably difficult, and will result in errors that need to be found through testing the integrated system. Since we didn't have engines in languages other than those mentioned above, we had no way to find and fix issues and verify that grammars in other languages were correct. Without being able to test, we can't ship, and without being able to ship there is no point in going through the effort in the first place.
Narrator, on the other hand, doesn't have anything complex that needs localizing, just strings. Localizing strings is part of the standard Windows localization process, so Narrator can support any language you have a TTS engine in.