Libraries for Voice Activity Detection (Not Speech Recognition)
In my answer to your that question, I had mentioned that Voice Activity Detection is a standard feature for codecs like G.729 and such others.  

You should look for reference encoders and decoders for algorithms that applies this.

One such example is - http://www.voiceage.com/openinit_g729.php

Another possible source is Speex codec. Which implements VAD

BTW: You should google "Voice Activity Detection" or "Talk Spurt" rather than "Speech Detection".