On the Ayreon website, Arjen Lucassen has revealed the final three singers that will make a guest appearance on the new Ayreon album.
"Vocalist number 15 is Wudstik, a Dutch hip hop and soul artist. Now don't run away, he actually loves rock as well! In fact his favorite bands include Dream Theater, Symphony X, Spock's Beard and Pain of Salvation. And obviously... Ayreon".
"Marjan Welman of the band Elister sent in a demo of her voice many years ago, and once again after her successful appearance in the Stream of Passion cover act "Team of Passion". Arjen's attention was drawn and he eventually invited her to sing a part on the new Ayreon".
The last singer to be announced through the vocalist guessing game (by releasing mp3 snippets) is Pain of Salvation's singer Daniel Gildenlöw.
2004 album The Human Equation also hosted a lot of guest appearances, including Dream Theater's James Labrie, Mikael Åkerfeldt from Opeth, Heather Findlay from Mostly Autumn, Devin Townsend and many others.