Android Speech Recognition as a service on Android 4.1 & 4.2

This is a work around for android version 4.1.1.

public class MyService extends Service{    protected AudioManager mAudioManager;     protected SpeechRecognizer mSpeechRecognizer;    protected Intent mSpeechRecognizerIntent;    protected final Messenger mServerMessenger = new Messenger(new IncomingHandler(this));    protected boolean mIsListening;    protected volatile boolean mIsCountDownOn;    private boolean mIsStreamSolo;    static final int MSG_RECOGNIZER_START_LISTENING = 1;    static final int MSG_RECOGNIZER_CANCEL = 2;    @Override    public void onCreate()    {        super.onCreate();        mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);         mSpeechRecognizer = SpeechRecognizer.createSpeechRecognizer(this);        mSpeechRecognizer.setRecognitionListener(new SpeechRecognitionListener());        mSpeechRecognizerIntent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);        mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,                                         RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);        mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,                                         this.getPackageName());    }    protected static class IncomingHandler extends Handler    {        private WeakReference<MyService> mtarget;        IncomingHandler(MyService target)        {            mtarget = new WeakReference<MyService>(target);        }        @Override        public void handleMessage(Message msg)        {            final MyService target = mtarget.get();            switch (msg.what)            {                case MSG_RECOGNIZER_START_LISTENING:                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)                    {                        // turn off beep sound                          if (!mIsStreamSolo)                        {                            mAudioManager.setStreamSolo(AudioManager.STREAM_VOICE_CALL, true);                            mIsStreamSolo = true;                        }                    }                     if (!target.mIsListening)                     {                         target.mSpeechRecognizer.startListening(target.mSpeechRecognizerIntent);                         target.mIsListening = true;                        //Log.d(TAG, "message start listening"); //$NON-NLS-1$                     }                     break;                 case MSG_RECOGNIZER_CANCEL:                    if (mIsStreamSolo)                   {                        mAudioManager.setStreamSolo(AudioManager.STREAM_VOICE_CALL, false);                        mIsStreamSolo = false;                   }                      target.mSpeechRecognizer.cancel();                      target.mIsListening = false;                      //Log.d(TAG, "message canceled recognizer"); //$NON-NLS-1$                      break;             }       }     }     // Count down timer for Jelly Bean work around    protected CountDownTimer mNoSpeechCountDown = new CountDownTimer(5000, 5000)    {        @Override        public void onTick(long millisUntilFinished)        {            // TODO Auto-generated method stub        }        @Override        public void onFinish()        {            mIsCountDownOn = false;            Message message = Message.obtain(null, MSG_RECOGNIZER_CANCEL);            try            {                mServerMessenger.send(message);                message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);                mServerMessenger.send(message);            }            catch (RemoteException e)            {            }        }    };    @Override    public void onDestroy()    {        super.onDestroy();        if (mIsCountDownOn)        {            mNoSpeechCountDown.cancel();        }        if (mSpeechRecognizer != null)        {            mSpeechRecognizer.destroy();        }    }    protected class SpeechRecognitionListener implements RecognitionListener    {        @Override        public void onBeginningOfSpeech()        {            // speech input will be processed, so there is no need for count down anymore            if (mIsCountDownOn)            {                mIsCountDownOn = false;                mNoSpeechCountDown.cancel();            }                           //Log.d(TAG, "onBeginingOfSpeech"); //$NON-NLS-1$        }        @Override        public void onBufferReceived(byte[] buffer)        {        }        @Override        public void onEndOfSpeech()        {            //Log.d(TAG, "onEndOfSpeech"); //$NON-NLS-1$         }        @Override        public void onError(int error)        {            if (mIsCountDownOn)            {                mIsCountDownOn = false;                mNoSpeechCountDown.cancel();            }             mIsListening = false;             Message message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);             try             {                    mServerMessenger.send(message);             }             catch (RemoteException e)             {             }            //Log.d(TAG, "error = " + error); //$NON-NLS-1$        }        @Override        public void onEvent(int eventType, Bundle params)        {        }        @Override        public void onPartialResults(Bundle partialResults)        {        }        @Override        public void onReadyForSpeech(Bundle params)        {            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)            {                mIsCountDownOn = true;                mNoSpeechCountDown.start();            }            Log.d(TAG, "onReadyForSpeech"); //$NON-NLS-1$        }        @Override        public void onResults(Bundle results)        {            //Log.d(TAG, "onResults"); //$NON-NLS-1$        }        @Override        public void onRmsChanged(float rmsdB)        {        }    }}

02/16/2013 - Fix beep sound if you use Text To Speech in your app make sure to turn off Solo stream in onResults

If you really want to implement continuous listening without internet connection you need to consider third-party packages, one of them is CMUSphinx, check Pocketsphinx android demo for example how to listen for keyword efficiently in offline and react on the specific commands like a key phrase "oh mighty computer". The code to do that 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:

@Overridepublic void onPartialResult(Hypothesis hypothesis) {    String text = hypothesis.getHypstr();    if (text.equals(KEYPHRASE))      //  do something} 

For any of you who are trying to silence the beep sound, regrading the @HoanNguyen answer which is very good but be careful as said in the api set setStreamSolo is cumulative so if there is in error in the speech recognition and on error is called(for example no internet connection) then setStremSolo true is called again and again which will result in your app silencing the whole phone (very bad)! the solution to that is to add the setStremMute(false) to the speechRecognizer onError.