One state-of-the-art framework is Kaldi, which is Open Source: http://kaldi.sourceforge.net/ http://kaldi.sourceforge.net/ You can even download trained models

One state-of-the-art framework is Kaldi, which is Open Source: http://kaldi.sourceforge.net/ http://kaldi.sourceforge.net/ You can even download trained models: http://kaldi-asr.org/ http://kaldi-asr.org/ It supports many state-of-the-art methods, like DNNs, sequence training, etc. So you can get quite good results with it. To train it yourself, of course you need some good training data from somewhere.