Music containing audible recordings of human voices that are either so quiet they can't possibly be distinguished from the rest of the music, or are so finely chopped and spliced that they end up becoming just a series of vocal sounds. Can also include samples of crowds which may be clearly audible, but so cacophonic that one would never be able to make out any individual voice.

This should not count if the voices are of actual original singing that just happens to be obscured by the music, as this is pretty common in certain genres such as shoegaze and they're usually accompanied with official lyrics.