Pook was hired [to contribute music to the movie “Eyes Wide Shut”] after choreographer Yolande Snaith rehearsed the masked ball orgy scene using Pook’s composition “Backwards Priests” – which features a Romanian Orthodox Divine Liturgy recorded in a church in Baia Mare, played backwards – as a reference track. Kubrick then called the composer and asked if she had anything else “weird” like that song, which was reworked for the final cut of the scene, with the title “Masked Ball”. -wikipedia