The sound effects of Stranger Things: how the sound team gave a voice to the Demogorgon, Dart and the demobats

A monster you hear before you see it

In the first episode of the series, on the night of November 6, 1983, a scientist runs down a corridor in the lab, steps into the elevator, and something grabs him from above. Henighan first designs the sound for this opening, from the corridor to Will's shed, everything before the title. With picture editor Dean Zimmerman, he keeps the corridor silent under the flickering lights, and the creature is heard in the elevator without being shown.

Henighan is contacted in late 2015 by Shawn Levy, director and producer, and by producer Rand Geiger. For the chapters of 1983 and 1984 he is the sound designer on a Technicolor team led by Brad North, supervising sound editor. From 1985 Henighan takes that post with William Files, who mixes with Mark Paterson. Sound effects editors Angelo Palazzo and Katie Halliday join in 1985, Lee Gilmore in 1986. Henighan, a Canadian-American who trained at Sheridan College, was nominated for the Oscar for Best Sound Mixing for Roma.

1. Late 2015 The first contact

   Henighan is brought in by Shawn Levy.

2. 2017 First Emmy for sound

   Sound editing, for The Upside Down, the eighth episode of 1983.

3. 2018 Second Emmy

   Sound editing, for The Mind Flayer.

4. 2020 Third Emmy

   Sound editing, for the eighth and final episode of 1985.

5. 2022 Two Emmys

   Sound editing and mix, for The Massacre at Hawkins Lab.

6. 2023 Two nominations

   Sound editing and mix, for The Piggyback.

1983: a seal behind the Demogorgon

Hiding in the shed behind the house, Will aims a rifle at the door. The bulbs flicker, the creature rises behind him, and both disappear. For this scene, small electrical sounds accompany the bulb, crickets and insects slow down, then silence comes before the title music.

Without knowing whether he has the job, Henighan sends the Duffers MP3s in the middle of the shoot: slowed insects, stretched baby cries. Three or four weeks later they write that they loved his idea for the creature, heard after a day of filming. First he rules out pigs, cats and any animal or human sound. Dry ice and squeaks fail. His own voice, run through Krotos's Dehumaniser, sounds overdone. He looks for a voice you recognize, loaded with unease and intelligence.

His sound library holds seal screams bought years earlier from Tim Prebble, who runs Hiss and a Roar, in New Zealand. First he buries them under other sounds, then he goes back to something simpler: a barely transposed and shortened scream. “The basic sound is that of a seal.” He liked twisting a light, cheerful sound into something frightening. For the flesh: water on flour, creaking doors, a yoga ball that squeaks, dry ice in the big roars. The creature's premix is called “Entity”, its 2015 name, which Henighan keeps.

He has not seen the gate in the lab. He supplies breaths and pulses. Matt Duffer, when he hears the growling breath, wants more of it. The gate's pulse has the rhythm of a heartbeat, which the team lifts in the mix when men pass through it.

1984: Dart, a man's voice and howler monkeys

On the evening of October 31, 1984, in the third episode of season 2, Dustin puts the small creature from his trash into his turtle's terrarium. It chirps, lets out a shrill scream when it gets too hot under the terrarium lamp, then takes the nougat he holds out. Brad North wanted Dart not to sound like a Demogorgon, because its nature only becomes clear later.

Henighan lends stages 1, 2 and 3 his own voice, sent through the Dehumaniser. He performs to picture: vocalizations, purrs, words, reactions, sometimes a hand over half his mouth or a sip of water. He wanted a tender, friendly tone. As Dart grows, the voice gets deeper. Once Dart becomes a demodog, Henighan adds more guttural sounds, vibrato and the roars of 1983: for him these creatures are cousins.

Dart's stretches on waking are the small morning squeaks of a baby, probably Brad North's child. Part of the pack's howling comes from howler monkeys Henighan had recorded years earlier on a trip to Tikal.

1984: a shadow with no mouth, tunnels that pulse

On November 1, 1984, at school, in the daytime, Will turns toward the shadow, shouts at it to go, and it rushes into him. The tornado arms coming down on him mix swarms of bees and waterfalls, treated with a fast tremolo, plus a Doppler effect for the smaller movements at the heart of the tornado.

The shadow, which the party will later call the Mind Flayer, is a thunderstorm: lightning, thunder, explosions and large electrical crackles, treated with phasing and flanging. Its screams come from large mammals, mostly elephants, from a few transposed vultures and a warthog. It has no face, Brad North says: no mouth opens, hence a wordless scream. The particles around it are cut-up insects, with tremolo. Henighan had then read only four scripts, and the visual effects were still rough.

Brad North records the growl of Ziggy, the little white dog Matt Duffer brought to the mix, and turns it into a scream for Will in a shadow sequence and a transition sound. The tunnels draw on the same sound vocabulary as the Upside Down, with a heartbeat Henighan devised. The gate, North says, breathes. The waves and the beat of the tunnels lead into the end of season 2, when Eleven confronts the gate, Henighan says. For Eleven's powers he digs out sounds from 1983 that he had not sent, synthetic and metallic risers. At the start of the second episode of 1984, in a flashback, these risers fight a sticky gate, which Eleven widens to leave the Upside Down.

1985: the gore season

On July 4, 1985, at Starcourt, Jonathan and Nancy search a car the group has just set back on its wheels. Max sees the monster walk across the glass roof, then it breaks through. This monster is the Mind Flayer's flesh body. Henighan wants the silence before the chaos: a few cracks, glass splitting, no voice, no heavy footsteps, then one or two heavier steps so you look up, and the roar. His reference: The Lost World: Jurassic Park, the camper at the edge of the cliff.

The monster's screams mix lions, tigers, some walrus, transposed dry ice, birds and small details from Henighan's voice. A squeaking ironing board is recorded straight through the Dehumaniser. For the tentacles searching for the hidden group, he mixes his voice, the board and the hisses of a cappuccino machine, recorded for the vines of 1984.

Matt Duffer announces a gore season. Henighan records raw chickens, slimy things from the supermarket, fruit and vegetables, watermelons and raw meat being torn. In his backyard, in the rain, steps in the mud in rubber boots make the monster's feet. For Eleven's leg, as far as he remembers, it was chicken bones breaking. The small screams of the thing that comes out recall the rats at the start of season 3, themselves a callback to the vines of 1984.

1986: a closet, vegetables and a breathing house

At the end of the sixth episode of season 4, Steve is pulled through the gate in the lake. In the Upside Down, bats attack him. Nancy, Robin and Eddie free him at the start of the next chapter. Palazzo gets the first scenes in October. Pig screams transposed upward do not work. What works is Palazzo's squeaking sliding closet door. Henighan, who had been thinking about it for two seasons, had a similar one. The two doors become the base of the demobats' voices. The wood bending and crackling does the rest. Lee Gilmore made the first versions. Palazzo also slips in a nod to the Demogorgons, because everything is connected through the hive.

Palazzo met Henighan on Robert Rodriguez's films, more than fifteen years ago, and received an Emmy for season 3. Started very early, the voice of Vecna is, along with the clock, one of Henighan's two big jobs that season. Working from the dailies, he compresses it hard, adds bass, sends it through a module called Manipulator and transposes it. Henighan says he knew not to do too much. Mark Paterson spreads it left, center and right, to give it width when needed.

The body is cabbage, carrots being broken, peppers being twisted, and tomatoes, wrapped in a wet cloth, so it sounds like bones cracking under the skin. Lee Gilmore adds cracking pumpkins. These sounds build the movements, then the vines of the Creel house, which attack the group. For the house, Palazzo records an old IKEA piece of furniture he wanted to get rid of: a footrest, the microphone pushed underneath, recorded at 192 kHz so it can be pitched down into the low end. Once transposed and mixed with other sounds, this bending wood gives the house a breathing quality. Poltergeist-style reversed whispers go into the sound hits, as far as he remembers.

The chime of the clock starts from a Westminster clock, with a cello at each swing, its muted strings struck with the bow, plus a slowed gong and a chime, sent by the Duffers. In the seventh episode of season 4, the guards loose a Demogorgon on the prisoners. For Palazzo, version 2.0 is the one he builds from all of Henighan's base sounds, the Upside Down, the Demogorgons and the dogs, made more aggressive. For Henighan, it is the name Palazzo gave to Hopper's fight against the Demogorgon in the prison, in the last chapter of 1986. For Hopper's blows in the prison, Palazzo wants a realistic, brutal tone.

Five or six creatures in the same battle

Warning: what follows discusses season 5. In November 1987, Demogorgons appear in the military base, where the army has gathered the children of Hawkins. Under a flamethrower's jet, Will and the creatures scream in pain, connected through the hive, before Will freezes three of them. The chapter is called Sorcerer.

Dean Zimmerman wanted the scene early, eight months before the interview Henighan gave in December 2025. Henighan hears a Saving Private Ryan mood in it, so there is little music. First he lays in the weapons of the time, AK-47s, rifles and Humvees, then the five or six Demogorgons of the battle: a delicate dance between the gunfire, the explosions and the roaring. Paterson and Files handle the final mix.

While working on the 1983 chapters, Henighan thought the series would have only one Demogorgon. The final season has six or seven, with voices from the same family, different enough to tell the one on the left from the one on the right. He also sometimes listens back to a sound from 1984 and thinks it would suit the gate, no longer remembering how he had made it. In 2026, the sound editing and mix of “The Rightside Up” are nominated for Emmys, but neither wins.

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