I’ve come across 1 free option on the Unity forums that uses a UDP server and the Microsoft Speech API. However, haven’t managed to get it to work:(
http://forum.unity3d.com/threads/windows-udp-voice-recognition-server.172758/
Also discovered this new plugin, UVoice, unfortunately no demos or trial versions available. Also confused as to whether it will work on OSX, or only Windows
Another possibility would be to use the powerful Google Speech API, but unfortunately I have been unable to find any Unity based demos or plugins.
Can any other Unity devs chime in or comment on the above? I’m really trying to find the most robust solution, whether free or commercial.