The ViaVoice Kit provide the necessary tools to develop applications that incorporate speech recognition using Linux
Openmind (Freespeech) is a free speech recognition project for Linux. It will be designed so that it can be easily integrated into any application or window manager as well as the KDE and Ggnome desktop environments.
Archive of messages on the Linux Viavoice mailinglist.
Festival is a general multi-lingual speech synthesis system developed at CSTR. It offers a full text to speech system with various APIs, as well an environment for development and research of speech synthesis techniques.
Special Synapse TAP Workstation translates speech into mouse events and keystrokes to control all environments - Unix, mainfame, and Mac with speech recognition.
Bayonne is the free multi-line telephony server of the GNU project. Source code available for LINUX/UNIX targeted towards messaging, IVR with considerable extensibility. Bayonne supports a modular architecture, native scripting and TGI.
Cvoicecontrol is a speech recognition system that allows users to convert spoken commands to Linux/unix commands. For KDE and X windows.