What the hell is that noise? The noise is hell.
A character within the story hears something odd. Unnatural. When they hear the sound once, it may not be that terrifying, but as time passes, they become more and more frightened. The sound gets scarier as it gains more and more relevance. Given time, the sound comes to haunt them, even away from the source. The sound has taken on a nightmarish relevance because of the setting. The sound could come from anywhere.
The trope isn't limited to a sentence, a catch phrase, or a song. The sound that terrifies the character can be made by the living, such as footsteps, a laugh, the call of a loud little animal. The sound may be made by the non-living, such as the creak of a chair, a door, a bouncing ball, the crackle of radio static, or any one of hundreds of other seemingly mundane noises. Often times it signals the coming of a yet-unseen threat, usually one you don't want to be anywhere near you, and hearing it is more than enough of a sign to tread carefully, brace yourself, or run. Better pray it doesn't mean that You Are Already Dead.
This isn't a Brown Note, a sound or image that causes involuntary action/harm. This trope is about the psychological effect of a repeated noise to the character(s) in the story. See also Hearing Voices, which can also be this depending on what kind of voices they are, and Nothing Is Scarier, which is almost the Visible Silence version of this. Sinister Scraping Sound is an intentional, psych-out type of hellish noise; if a noise foreshadowing a threat is produced by something attached to, or ingested by, that threat, it's The Croc Is Ticking.
- In Supergirl storyline Bizarrogirl, Dr. Light and Gangbust are examining what appears to be a Kryptonian rocket ship when they hear a strange noise in the darkness. Alarmed, the duo become alert right before being ambushed by Bizarrogirl.
- A variation on this happens in one of the EC Comics stories, wherein a king's daughter falls to her death while he is enjoying himself at a party, and her scream keeps ringing in his ears afterwards in every sound he hears, starting with the local church bells (he has them melted down), the movements of the castle inhabitants (he has them wrap their feet in soft cloth), and even the sounds of people working in town (he has them cease working). Unfortunately his quest for absolute silence reaches a head when his ears become so sensitive that he can hear the people breathing. He orders them to stop breathing, and finally he is beset by an angry (and loud) mob. One of them, a clockmaker, sews a clock inside the king's chest that automatically wound itself up at the slightest movement and took hours to run down. The king is left lying on a bed, hardly daring to move, hardly daring to breathe, so as not to trigger the clock. Then a spider comes down on a silk line, heading for his face...
- Children of an Elder God: In the prologue, two scientists and a team of spelunkers are exploring a network of caverns when they hear several faint, faraway screams. They freak out right away:
[There are faint screams in the distance]
Home Base (Speaker unidentified): What the hell was THAT?
- Quicken: When Emma goes nuts, she screams. Her scream sounds so scary and inhuman than her assailants step back.
A switch was suddenly flipped inside me. Something primal and inarticulate tore its way out of my throat, a sound I could have never imagined that I could make.
- SCP-682s roar.
- Lessons from the Mountain has Morgoth's laughter. Over five hundred years battling monsters, and Maedhros still considers his laughter to be the most frightful sound he has ever heard.
Maedhros: I proudly told him that he may kill me or torture me, but that would never be. He laughed. I think that was the most awful sound I have ever heard, and I have heard many things that no one should hear.
- In the song "Spooky Scary Skeletons" by Andrew Gold, the titular skeletons, despite being "shy" and "silly", are still considered scary because they "speak with such a screech", "shriek", and "shout startling shrilly screams".
- The Ur-Example may very well come from Classical Mythology: the god Pan loved to scare the shit out of lonely travelers by hiding nearby and letting out a bloodcurdling scream. Ever wonder where we get the word "panic?" Now you know.
- Similar to Pan is the skinwalker of Navajo folklore. It initially freaks out its victim with two loud whistling noises that can be heard for miles. Its "speech" sounds like a distorted voice or animal call.
- A number of youkai are know to torment travelers by making sudden and terrifying noises, like the kerakera onna (a giant, ghostly woman who haunts brothel patrons with an Evil Laugh only her victim can hear), or Hachishaku-sama (Ms. Eight-Foot-Tall), who stalks young children and can imitate the voices of their loved ones but can only make a terrifying "po-po-po" sound otherwise.
- La Llorona (The Weeping Woman) from Latin American folklore is very well known for her piercing, otherworldly screams of "¡Ay mis hijos!" ("Oh, my sons!"). To this day, many people are still very terrified of her and believe her laments are an omen for dreadful times.
- The Magnus Archives:
- The whistled tune that the narrator of "First Hunt" hears as he and his friend hunt portends something very bad. The tune is "A-hunting we shall go".
- In "Boatswain's Call" the mate on a modern ship carries the eponymous old-fashioned whistle. As the narrator finds herself in the midst of a disturbing trip in the (also strangely old-fashioned) lifeboat with the crew, the mate blows it, making a sound that is unnaturally and disturbingly shrill and piercing, yet somehow also sounds far away. Of course, this signals that things are about to go From Bad to Worse.
- Grisaia no Kajitsu: The clicking sound of Yumiko's boxcutter is something you learn to fear in Mihama Academy, as it indicates that it's wielder is royally pissed.
- Mosquito Miscreants. Go, try to sleep with one of those lil buggers circling over you (even in a no-malaria zone), instead of bringing some slipper fu wrath on her. If you manage that, you may even skip the entry test for Buddhist monks.
- You let your PC running, doing something else, and suddenly ka-system-ploing! Unless its the sound of an incoming message, it will strike anxiety into any user. (Upgrade to sheer panic if your unsaved great unfinished novel is under work.)
- Koala bears, in contrast to their cuddly appearance, sound like demonspawn when upset.
- The sound of an Emergency Broadcast qualifies as this, mostly for the knowledge that, unless it's a test, something has gone horribly wrong in the world.