This is really an old trick, but worth to show again.
You can use most types of sound-files, using mostly MP3 and such myself.
It’s pretty easy and straightforward:
- connect phone to computer (shown on windows 8 here), open the storage.
- Choose to either, you don’t have to create all. If you just want custom alarms, just create the alarms folder:
- create folders notifications, alarms and ringtones as separate folders.
- [shown as gallery] Create a folder called Media and in that create a folder called Audio, and under that create alarms, notifications and ringtones
- Copy the sounds you want to use into the folder of choice.