Arnab Ghoshal and Dan Povey introduce the Kaldi speech recognition toolkit in the IEEE Speech and Language Technical Committee newsletter: http://www.signalprocessingsociety.org/technical-committees/list/sl-tc/spl-nl/2012-02/kaldi/
Kaldi is a free open-source toolkit for speech recognition research. It is written in C++ and provides a speech recognition system based on finite-state transducers, using the freely available OpenFst, together with detailed documentation and scripts for building complete recognition systems. The tools compile on commonly used Unix-like systems and on Microsoft Windows. The goal of Kaldi is to have modern and flexible code that is easy to understand, modify, and extend. Kaldi is released under the Apache License v2.0, which is highly nonrestrictive, making it suitable for a wide community of users. Kaldi is available from SourceForge.