However fans might feel about its various seasons, the "American Horror Story" opening credits never disappoint.

The award-winning work of Kyle Cooper and his Prologue Studio mixes stop-motion with CGI to create a dreamlike procession of the strange and undead. It's not hard to see how those flickering visuals give us the creeps, and paired with a hair-raising soundtrack, the "AHS" title sequence becomes a perfect nightmare.

But, that song -- filmy, discordant -- was never supposed to end up in a horror show. It wasn't even supposed to be scary.

The "AHS" theme song used in all five seasons' worth of openers was originally created by César Dávila-Irizarry in 1998, when he was a sophomore at the University of Puerto Rico enrolled in a course on music history. He'd been experimenting with digital and practical sounds when he pieced the track together using Cool Edit 96 on a bulky, Windows 98-equipped computer.

"When I created the song back in '98, I was not aiming for horror," Dávila-Irizarry, now an audio designer, wrote to The Huffington Post.

He'd wanted to see what would happen when he recorded certain sounds, stretched them out, and mixed them with other digital noise. It was a process. His computer was so slow, Dávila-Irizarry recalled, that he could drive to Blockbuster, rent a movie, get home and watch it in the time it took the machine to do its job stretching just one file. Now, he tells us, such a task takes a computer mere seconds.

What we're really hearing in the "AHS" theme are a bunch of typical noises recorded around Dávila-Irizarry mother's Puerto Rican home, he explained, slowed down and manipulated in strategic ways (the specifics of which he says he'll bring to his grave, so as not to totally ruin the magic for us).

That really jarring moment about seven seconds in, though? It's just some metal clothes hangers dropping on a tile floor. Later on, you can just barely make out rain drops falling on his windows. Digital white noise makes up other portions.

Mundane as they may be, these noises speak to us on an unconscious level, David Holmes, senior lecturer in psychology at Manchester Metropolitan University, told HuffPost -- particularly surprising metal noises.

"These actually rely on a principle we've got embedded in us, which is an evolutionary response to bits of grit being caught in your teeth and scraping down the side," Holmes said. "Because in the old days, we might be swallowing bones and rocks and all sorts of things."

Noises that somehow mimic frightened animals' screams or snapping twigs -- termed "nonlinear" sounds, he explained -- prompt uneasiness for similar reasons.

It's worth noting that what we hear on "AHS" is no longer the literal cacophony of Dávila-Irizarry's home, but a recreation. When he was done with the track, Dávila-Irizarry gave it to a friend, video editor Gabriel Diaz. Years later, Diaz dusted it off to use as a placeholder in the first season's opener -- not knowing everyone would like it so much that they would want to keep it in. For technical (and some legal) reasons, FX recruited Nine Inch Nails' Charlie Clouser to recreate the track. The original composer was busy with other projects at the time, although he said Clouser's handiwork sounds pretty identical to his original.

This season's opener builds on Dávila-Irizarry's and Clouser's track even more.

For the "Hotel" opening credits, composer Mac Quayle layered in a synthetic melody over the tune we'd gotten used to, adding a sort of gothic Roaring '20s sound. (Fans can probably expect more opening-sequence variation in future seasons.)

As some have started calling the opening sequence the scariest part of the whole show, we can imagine how "AHS" might elicit fewer thrills set to a more chipper soundtrack.

So as those terrors -- ghostly children, a skeletal woman in moth-eaten lace -- flash before your screen, remember the college student recording a bunch of ho-hum closet organizers dropping to the floor, the former rockstar charged with recreating it note for note, and the sound guy shrouding it all in faux strings.

﻿Clarification: This article previously referred to Mac Quayle as the show's sound designer; he wrote the show's score, and his title has been updated accordingly.

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