Board Thread:Support Requests - Getting Technical/@comment-35340256-20150602091132/@comment-303594-20150602091850

OGG vorbis is a free sound file format. Formats like MP3 have patent issues meaning that it's difficult to impossible to provide free editing software for them. OGG, on the other hand doesn't have any of these issues.

You can use the free Audacity program to create OGG files.