I want to check the loudness of voice in android

Question

I am developing an application where I have to detect the loudness of voice. Means some on shouts on the mobile and it will show the loudness level on the screen.

Which API can be used for this?

Answer 1

Look at http://developer.android.com/reference/android/media/AudioRecord.html

When you read the buffer the byte values will represent the amplitude. The higher the byte value the louder the sound.

Here is a scaled-down version of something I used in an app I wrote a while back:

Add this to your mainifest.xml
<uses-permission android:name="android.permission.RECORD_AUDIO" />

soundlevel.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ToggleButton
        android:id="@+id/togglebutton_record"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ToggleButton" />


    <ProgressBar
        android:id="@+id/progressbar_level"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

SoundLevel.java

import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.widget.CompoundButton;
import android.widget.ProgressBar;
import android.widget.ToggleButton;

public class SoundLevel extends Activity {

    private static final int sampleRate = 11025;
    private static final int bufferSizeFactor = 10; 

    private AudioRecord audio;
    private int bufferSize;

    private ProgressBar level;

    private Handler handler = new Handler();

    private int lastLevel = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.soundlevel);

        level = (ProgressBar) findViewById(R.id.progressbar_level);

        level.setMax(32676);

        ToggleButton record = (ToggleButton) findViewById(R.id.togglebutton_record);

        record.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                // TODO Auto-generated method stub

                if (isChecked) {
                    bufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT) * bufferSizeFactor; 

                    audio = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize);

                    audio.startRecording();

                    Thread thread = new Thread(new Runnable() {
                        public void run() {
                            readAudioBuffer();
                        }     
                      });

                    thread.setPriority(Thread.currentThread().getThreadGroup().getMaxPriority());

                    thread.start();

                    handler.removeCallbacks(update);
                    handler.postDelayed(update, 25);

                } else if (audio != null) {
                    audio.stop();
                    audio.release();
                    audio = null;
                    handler.removeCallbacks(update);
                }

            }
        });
    }

    private void readAudioBuffer() {

        try {
            short[] buffer = new short[bufferSize];

            int bufferReadResult;

            do {

                bufferReadResult = audio.read(buffer, 0, bufferSize);

                for (int i = 0; i < bufferReadResult; i++){

                    if (buffer[i] > lastLevel) {
                        lastLevel = buffer[i];  
                    }

                }

            } while (bufferReadResult > 0 && audio.getRecordingState() == AudioRecord.RECORDSTATE_RECORDING);

            if (audio != null) {
                audio.release();
                audio = null;
                handler.removeCallbacks(update);

            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    private Runnable update = new Runnable() {

        public void run() {

            SoundLevel.this.level.setProgress(lastLevel);

            lastLevel *= .5;

            handler.postAtTime(this, SystemClock.uptimeMillis() + 500);

        }

    };
}