Change the projection to get MediaStore.Audio.Media.DATA column in the query.
mCursor = managedQuery(
MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
new String[] { MediaStore.Audio.Media.DISPLAY_NAME,
MediaStore.Audio.Media.DATA},
Audio.Media.DATA + " like ? OR " + Audio.Media.DATA + " like ? ",
new String[] {"%mp3","%wav"},
"LOWER(" + MediaStore.Audio.Media.TITLE + ") ASC");