Pretty much all of their songs are this! The amount of Hell Is That Noise and Sensory Abuse within them (particularly their later songs) can make it easy to see why at least someone would be unsettled, if not outright terrified.
Seriously though, do not listen to their songs if it's late at night or you're in a dark room. No really, DON'T.
Incunabula isn't as unsettling as their later albums, but a good chunk of the songs on there such as ''Bronchus 2'', ''Kalpol Introl'' and to a lesser extent ''Lowride'', can still give out the chills.
"Nuane", the last track on Chiastic Slide - especially its ending, which is one long, droning bass that is accompanied by a salvo of beeping and buzzing sounds (think computer hardware). This all goes on uninterrupted for about 3 minutes, when the song fades out.
"Gantz Graf" has so much Sensory Abuse that it's sure as hell something that resembles the chaos theory. Listen to it for yourself here. Enjoy.
Quaristice. This is quite possibly the darkest and most haunting out of all the Autechre albums - indeed, this is where their sound is arguably at its most avant-garde. There's plenty of tracks on their with their own sounds and indeed own ways of terrifying you.
IO has an unsettling melody that repeats for the entire song... as well as a voice sample that's highly muffled and cracks a lot. Oh, and because Autechre are Autechre, it glitches a load too.
Fol3.What the hell are those sounds?! This song is so avant-garde, there's almost no pattern to it that can be made out. A different part of the song is thrown randomly at any moment.
WNSN is another offender. At least it's possible to make out a pattern in the song though...
Outh9X is just plain unnerving. It sounds like horror game music.
"Shimripl casual" from NTS Session 4 feels like waking up in and exploring a strange, unknown landscape with a constant sense of dread throughout.
Confield, otherwise known as "Hell Is That Noise: The Album." It was around this point where their songs started to sound a lot darker and more chaotic, not to mention haunting...
"Eidetic Casein" has some downright terrifying sounds that can only be described as those you'd hear if a carousel was having a breakdown.
Of note are the two tracks, "Parhelic Triangle" and "Bine", both of which are considered to be some of Autechre's most terrifying songs. The former is a rather eerie tune that drifts and crackles with ominous bell tones heard throughout, and the latter is a frantic, fast-paced wall of strange beats and horrifying sounds that may send one's paranoia levels through the roof.
"Lentic Catachresis", the ending track of the album, feels like the end of all madness; it starts with some distorted robotic voices and moody, yet creepy and depressing synths, until it suddenly speeds up and stays that way for a while until it just as suddenly glitches and fizzles out. In other words, Confield's ending feels more like an abrupt stop or even a death than a true ending.
"Fermium" from Untilted is another one packed with hellish Sensory Abuse (as are all of the songs on that album), but the last 60 seconds can get especially horrifying.
The music video for "Second Bad Vilbel". It consists of a lot of cryptic and odd imagery, such as a faceless humanoid with an enlarged hand (pictured above), and a robotic creature that sits in a blank room and later outside in some water, which mostly just stands motionless in place until it "transforms" midway through.
The song itself is ominous, what with the loud static, heavy beats, and dark drones. It all adds to the video's eeriness.
The Japanese bonus track for PLUS, "p1p2", which consists of unnerving howling and low bell noises.
, ''Kalpol Introl''