Many years ago, my good friend and fellow scrivener of scariness, William R. "Mr. Bill" Trotter, gave me a tape of some dark music he thought I might enjoy. Among the many excellent selections were Ingram Marshall's Hidden Voices, which may be the eeriest piece of music I've ever heard. Much like Ennio Morricone's Carpenter-esque soundtrack to The Thing, Hidden Voices, when played in an otherwise silent, dark room, is almost enough to make me turn on all the lights in the house and put on some lighthearted death metal.
It's a disconcerting, minimalist composition, featuring mostly human voices, distorted and warped, that conjure up a nightmarish yet strangely beautiful atmosphere. To my mind, it's the perfect soundtrack for Lovecraft's "Dreams in the Witch House."

Hidden Voices is difficult to find on CD anymore; it's on an album titled Three Penitential Visions/Hidden Voices, which includes three other tracks. For Christmas, I received a nice iTunes gift certificate, and I was thrilled to find that the entire album is available on iTunes for $9.99 (in fact, you have to purchase the entire thing; you can't get just the individual tracks). It's well worth it; Hidden Voices is by far the strongest and most distinctive composition on the album, but the others are none too shabby. If you've got a hankering to listen to something that will likely raise the hairs on the back of your neck, Hidden Voices is the ticket.