Da Wikipedia:
There is currently no open-source equivalent of proprietary speech recognition software (e.g. Nuance's Dragon NaturallySpeaking or Windows Speech Recognition) for GNU/Linux. However, there are several incomplete, open-source projects and solutions that could be used to attain some elements of speech recognition in the free operating system. It is also possible to use Windows speech recognition software under GNU/Linux.
Também da Wikipedia:
Solutions
The following is a list of current projects dedicated to implementing speech recognition in Linux, as well as major (though mostly incomplete) native solutions that are available as of March 2008:
*CVoiceControl is a KDE and X Window independent version of its predecessor KVoiceControl
*DynaSpeak from SRI International (speaker-independent speech recognition software development kit that scales from small- to large-scale systems, for use in commercial, consumer, and military applications)
*CMU Sphinx is a general term to describe a group of speech recognition systems developed at Carnegie Mellon University.
*GnomeVoiceControl is a dialogue system to control the GNOME Desktop that was developed in the Google Summer of Code in 2007.
*Julius is a high-performance, two-pass large vocabulary continuous speech recognition (LVCSR) decoder software for speech-related researchers and developers.
*LumenVox Speech Engine is a commercial library for Linux and Windows for inclusion in other software. It has been integrated into the Asterisk private branch exchange system [2]
*Open Mind Speech a part of the Open Mind Initiative and aims to develop free (GPL) speech recognition tools and applications, as well as collect speech data.
*PerlBox is a perl based control and speech output.
*Simon (This project aims at being extremely flexible to compensate dialects or even speech impairments; requires HTK and Julius)
*VoxForge is a free speech corpus and acoustic model repository for open source speech recognition engines.
*Xvoice (requires ViaVoice to function)
*Verbio ASR is a commercial speech recognition server for Linux and windows platforms.
*Platypus is a open source shim that will allow Dragon NaturallySpeaking running under wine to work with any linux x11 application.
*Vedics is a speech assistant for GNOME Environment
Provavelmente para usar qualquer uma dessas ferramentas, você mesmo deve escrever algum tipo de roteiro. Boa sorte!