Playing the default notification sound of the device is the most effective way to notify a user. This can be established by getting the Uri of the audio file from RingtoneManager. To play default alarm tone , ringtone or notification sound from an android app, the following code snippet is useful.
Play Notification Tone
try {
Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
r.play();
} catch (Exception e) {
e.printStackTrace();
}
Play Alarm Tone
To play an Alarm-tone change TYPE_NOTIFICATION to TYPE_ALARM.
try {
Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
r.play();
} catch (Exception e) {
e.printStackTrace();
}
Set & Play a Tone from Raw resources folder
To set a file from the raw folder of your app just change the uri to get the desired file from raw resources. If you have included a tone called sownd.mp3 in your raw resources folder, all you have to do is change
Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
to
Uri path = Uri.parse("android.resource://"+getPackageName()+"/raw/sound.mp3");
The code should look like this now
try {
Uri path = Uri.parse("android.resource://"+getPackageName()+"/raw/sound.mp3");
// The line below will set it as a default ring tone replace
// RingtoneManager.TYPE_RINGTONE with RingtoneManager.TYPE_NOTIFICATION
// to set it as a notification tone
RingtoneManager.setActualDefaultRingtoneUri(
getApplicationContext(), RingtoneManager.TYPE_RINGTONE,
path);
Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), path);
r.play();
}
catch (Exception e) {
e.printStackTrace();
} 
