"The Real Song for the Deaf" is a hidden pregap track on the album Songs for the Deaf by Queens of the Stone Age.
It starts off with a voice saying, "Huh? What?" and the rest is low frequency noises. When listening to Songs for the Deaf on a CD player, go to the first track on the album and rewind to -1:32. The track will then play.
Deaf people can actually "hear" this by feeling the frequencies.