Restrict speech Recognition to Alpha-numeric words

Question

I want to use the Speech Recongnition to handle commands in my application. I know at any given point in my application what the valid commands would be at that point so would like to limit the results that the Speech Recongnition is matched against.

I mean in my app .. The valid words are only numbers plus alphabets. I mean number like A13FG6 something like that.

I would like to be able to restrict the Speech recongnition to only try and match against alphaNumeric words.. Limiting the vocabularly would enhance its chance of success..

how could i modify the given code to fulfill my requirement

Thanks in advance..

import java.util.ArrayList;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.speech.RecognitionListener;
import android.speech.RecognizerIntent;
import android.speech.SpeechRecognizer;
import android.util.Log;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

    private TextView mText;
    private SpeechRecognizer sr;
    private static final String TAG = "MyStt3Activity";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button speakButton = (Button) findViewById(R.id.btn_speak);
        mText = (TextView) findViewById(R.id.textView1);

        Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
                RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
       intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,
           getClass().getPackage().getName());

        SpeechRecognizer recognizer = SpeechRecognizer
                .createSpeechRecognizer(this.getApplicationContext());
        RecognitionListener listener = new RecognitionListener() {
            @Override
            public void onResults(Bundle results) {
                ArrayList<String> voiceResults = results
                        .getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
                if (voiceResults == null) {
                    Log.e(TAG, "No voice results");
                } else {
                    Log.d(TAG, "Printing matches: ");
                    for (String match : voiceResults) {
                        Log.d(TAG, match);
                        mText.setText("results: " + match);
                    }
                }
            }

            @Override
            public void onReadyForSpeech(Bundle params) {
                Log.d(TAG, "Ready for speech");
            }

            @Override
            public void onError(int error) {
                Log.d(TAG,
                        "Error listening for speech: " + error);
            }

            @Override
            public void onBeginningOfSpeech() {
                Log.d(TAG, "Speech starting");
            }

            @Override
            public void onBufferReceived(byte[] buffer) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onEndOfSpeech() {
                // TODO Auto-generated method stub

            }

            @Override
            public void onEvent(int eventType, Bundle params) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onPartialResults(Bundle partialResults) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onRmsChanged(float rmsdB) {
                // TODO Auto-generated method stub

            }
        };
        recognizer.setRecognitionListener(listener);
        recognizer.startListening(intent);


/*      speakButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                Intent intent = new Intent(
                        RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
                // intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
                intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, "en-US");
                intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,
                        getClass().getPackage().getName());

                intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 5);
                sr.startListening(intent);

                // startActivityForResult(intent, 1010);
                Log.i("111111", "11111111");
            }
        });*/
    }
}

Answer 1

You can not restrict recognition in Android Speech API, it doesn't support grammars. However, you can try CMUSphinx. See the example under link, you can define a grammar to use alpha digits only, it will work offline so the response will be very fast and you can tune accuracy for the best match too.