title: Android Notification builder sound doesn't work
body: <p>I have tried many things suggested here, but nothing works for me.
  here is my source code:</p>
  
  <pre><code>Intent resultIntent = new Intent(this, MainActivity.class);
  PendingIntent contentIntent = PendingIntent.getActivity(this, 0, resultIntent,PendingIntent.FLAG_UPDATE_CURRENT);  
  NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)
  .setSmallIcon(R.drawable.ic_launcher)
  .setContentTitle("title")
  .setContentText("Hello World!");
  mBuilder.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION));
  mBuilder.setContentIntent(contentIntent);
  NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
  mNotificationManager.notify(0, mBuilder.build());
  </code></pre>
  
  <p>The notification appears but no sound, any help ?</p>