Speech Recognition API

Solution 1:

The two major open source speech-recognition engines in Ubuntu are Julius and Pocketsphinx. Both of these are quite low-level research projects, and you'll need to do a lot of reading and experimenting to be able to use them: they're not simple install-and-go projects. Simon Listens, as mentioned above, is a simple install-and-go project, and the Simon Listens project has a specific installation for Ubuntu -- http://www.cyber-byte.at/wiki/index.php/Installation#Ubuntu has instructions on how to enable it -- but that only works with 10.04, not the recently-released 10.10. (Hopefully the Simon Listens project will make a 10.10 version available soon.)

Solution 2:

There's the Java Speech API which works cross-platform...

Solution 3:

Also have a look at Simon Listens which is using the Open-Source Large Vocabulary CSR Engine Julius.