"Ambience 4" was the filename of an unused music track that could be previously found in the cache. The track is a shorter version of Fade Test. It was added in the Runescape 2 beta, but it is unknown where it was intended to play. It was removed from the game files on 26 September2019.
The track has a copyright date of 2003 rather than the usual 2003-04, as it was not updated when the Music Player was released.