If you want to assign different ringtones to some specific contacts on your Android phone then the option to do that is integrated into Android OS. Follow the given steps to apply ringtone to a contact on Android.
Note: This guide is written for Android 4.0.4 but it also works well on Android 4.1.
Assign Ringtone to a Contact on Android
Tap on App Drawer and open “Contacts” or “People”
Navigate to the contact from list to which you want to assign ringtone and tap on it
Tap on menu button on your mobile to open up Menu on screen and select “Set ringtone” option there
Select the ringtone of your choice from the list of available options and click OK button
Just close the app and thats it, you have assigned custom ringtone to a specific contact on Android, whereas rest of contacts have a default ringtone.