This is a simple example to create an app to detect Noise. When Noise/Sound frequency cross thersold vaule, You will get an alert.
Follow these steps:
1. Create an android project.
2.Create a Main activity (NoiseAlert.java)
SoundLevelView class is used to draw a sound meter on view ( Called in main.xml file ).
4. Create the src/YOUR PACKAGE/SoundMeter.java to record noise/sound. and paste following code :
4. Open AndroidMainifest.xml :
Add Permission
Thats it.
Note: You can run this apps only on live devices. But before installing this apps on your mobile, Please check the list of sensors running on you mobile.
Follow these steps:
1. Create an android project.
2.Create a Main activity (NoiseAlert.java)
import android.app.Activity;3. Create the src/YOUR PACKAGE/SoundLevelView.java and paste following code :
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.PowerManager;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;
public class NoiseAlert extends Activity {
/* constants */
private static final int POLL_INTERVAL = 300;
/** running state **/
private boolean mRunning = false;
/** config state **/
private int mThreshold;
private PowerManager.WakeLock mWakeLock;
private Handler mHandler = new Handler();
/* References to view elements */
private TextView mStatusView;
private SoundLevelView mDisplay;
/* data source */
private SoundMeter mSensor;
/****************** Define runnable thread again and again detect noise *********/
private Runnable mSleepTask = new Runnable() {
public void run() {
//Log.i("Noise", "runnable mSleepTask");
start();
}
};
// Create runnable thread to Monitor Voice
private Runnable mPollTask = new Runnable() {
public void run() {
double amp = mSensor.getAmplitude();
//Log.i("Noise", "runnable mPollTask");
updateDisplay("Monitoring Voice...", amp);
if ((amp > mThreshold)) {
callForHelp();
//Log.i("Noise", "==== onCreate ===");
}
// Runnable(mPollTask) will again execute after POLL_INTERVAL
mHandler.postDelayed(mPollTask, POLL_INTERVAL);
}
};
/*********************************************************/
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Defined SoundLevelView in main.xml file
setContentView(R.layout.main);
mStatusView = (TextView) findViewById(R.id.status);
// Used to record voice
mSensor = new SoundMeter();
mDisplay = (SoundLevelView) findViewById(R.id.volume);
PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "NoiseAlert");
}
@Override
public void onResume() {
super.onResume();
//Log.i("Noise", "==== onResume ===");
initializeApplicationConstants();
mDisplay.setLevel(0, mThreshold);
if (!mRunning) {
mRunning = true;
start();
}
}
@Override
public void onStop() {
super.onStop();
// Log.i("Noise", "==== onStop ===");
//Stop noise monitoring
stop();
}
private void start() {
//Log.i("Noise", "==== start ===");
mSensor.start();
if (!mWakeLock.isHeld()) {
mWakeLock.acquire();
}
//Noise monitoring start
// Runnable(mPollTask) will execute after POLL_INTERVAL
mHandler.postDelayed(mPollTask, POLL_INTERVAL);
}
private void stop() {
Log.i("Noise", "==== Stop Noise Monitoring===");
if (mWakeLock.isHeld()) {
mWakeLock.release();
}
mHandler.removeCallbacks(mSleepTask);
mHandler.removeCallbacks(mPollTask);
mSensor.stop();
mDisplay.setLevel(0,0);
updateDisplay("stopped...", 0.0);
mRunning = false;
}
private void initializeApplicationConstants() {
// Set Noise Threshold
mThreshold = 8;
}
private void updateDisplay(String status, double signalEMA) {
mStatusView.setText(status);
//
mDisplay.setLevel((int)signalEMA, mThreshold);
}
private void callForHelp() {
//stop();
// Show alert when noise thersold crossed
Toast.makeText(getApplicationContext(), "Noise Thersold Crossed, do here your stuff.",
Toast.LENGTH_LONG).show();
}
};
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
class SoundLevelView extends View {
private Drawable mGreen;
private Drawable mRed;
private Paint mBackgroundPaint;
private int mHeight;
private int mWidth;
private int mThreshold = 0;
private int mVol = 0;
public SoundLevelView(Context context, AttributeSet attrs) {
super(context, attrs);
mGreen = context.getResources().getDrawable(
R.drawable.greenbar);
mRed = context.getResources().getDrawable(
R.drawable.redbar);
mWidth = mGreen.getIntrinsicWidth();
setMinimumWidth(mWidth*10);
mHeight = mGreen.getIntrinsicHeight();
setMinimumHeight(mHeight);
//Used to paint canvas background color
mBackgroundPaint = new Paint();
mBackgroundPaint.setColor(Color.BLACK);
}
public void setLevel(int volume, int threshold) {
if (volume == mVol && threshold == mThreshold) return;
mVol = volume;
mThreshold = threshold;
// invalidate Call onDraw method and draw voice points
invalidate();
}
@Override
public void onDraw(Canvas canvas) {
canvas.drawPaint(mBackgroundPaint);
for (int i=0; i<= mVol; i++) {
Drawable bar;
if (i< mThreshold)
bar = mGreen;
else
bar = mRed;
bar.setBounds((10-i)*mWidth, 0, (10-i+1)*mWidth, mHeight);
bar.draw(canvas);
}
}
}
SoundLevelView class is used to draw a sound meter on view ( Called in main.xml file ).
4. Create the src/YOUR PACKAGE/SoundMeter.java to record noise/sound. and paste following code :
import java.io.IOException;
import android.media.MediaRecorder;
public class SoundMeter {
// This file is used to record voice
static final private double EMA_FILTER = 0.6;
private MediaRecorder mRecorder = null;
private double mEMA = 0.0;
public void start() {
if (mRecorder == null) {
mRecorder = new MediaRecorder();
mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mRecorder.setOutputFile("/dev/null");
try {
mRecorder.prepare();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mRecorder.start();
mEMA = 0.0;
}
}
public void stop() {
if (mRecorder != null) {
mRecorder.stop();
mRecorder.release();
mRecorder = null;
}
}
public double getAmplitude() {
if (mRecorder != null)
return (mRecorder.getMaxAmplitude()/2700.0);
else
return 0;
}
public double getAmplitudeEMA() {
double amp = getAmplitude();
mEMA = EMA_FILTER * amp + (1.0 - EMA_FILTER) * mEMA;
return mEMA;
}
}
4. Open AndroidMainifest.xml :
Add Permission
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
Thats it.
Note: You can run this apps only on live devices. But before installing this apps on your mobile, Please check the list of sensors running on you mobile.
