CMUSphinx has recently implemented continuous listening on Android platform. You can find the demo on the wiki page
You can configure one or multiple keywords to listen to, the default keyword is "oh mighty computer". You also can configure the detection threshold. Currently supported languages are US English and few others (French, Spanish, Russian, etc). You can train your own model for your language.
Listening is simple, you create a recognizer and just add keyword spotting search:
recognizer = defaultSetup()
.setAcousticModel(new File(modelsDir, "hmm/en-us-semi"))
.setDictionary(new File(modelsDir, "lm/cmu07a.dic"))
.setKeywordThreshold(1e-5f)
.getRecognizer();
recognizer.addListener(this);
recognizer.addKeywordSearch(KWS_SEARCH_NAME, KEYPHRASE);
switchSearch(KWS_SEARCH_NAME);
and define a listener:
@Override
public void onPartialResult(Hypothesis hypothesis) {
String text = hypothesis.getHypstr();
if (text.equals(KEYPHRASE))
// do something
}