Stranger Things Lead Sound Effects Editor Reveals Delightfully Unexpected (And Effective) Sources For The Demo-Bats In Season 4

Spoilers ahead for Vol. 1 of Stranger Things Season 4, because Demo-Bats are ahead!

It’s not a season of Stranger Things unless the record-breaking Netflix series introduces some new monsters to make fans very happy that they don’t have any open portals to the Upside Down to worry about in real life. Vecna – who was created using impressive practical effects on actor Jamie Campbell Bower – is the big bad menacing the people in Hawkins, but as Steve learned as soon as he passed through Watergate, the vicious Demo-Bats are to be feared in the Upside Down. The screeching and squeaking of the new monsters means horrors are on the way, and lead sound effects editor Angelo Palazzo explained the not-so-horrifying but totally effective sources behind their sounds. 

Stranger Things has introduced the Demogorgon as the terrifying creature that can more than hold its own against even multiple people at once, the Demodogs that can murder their way through a lab as a pack, and now the Demo-Bats that would have killed Steve if not for the arrival of his friends. Even then, he still lost his pound of flesh. According to the lead sound effects editor, finding the sound for the bats meant embracing the kinds of terror that they bring to the show. Angelo Palazzo said:

It seems like every season there's a new introduction of another level of demon or creature or another part of the hive mind. So yeah, this season is the bats, when they're these swarms of just vicious pirahna-like, berserker-like [creatures]. They function at one level, like full blast, attack mode at all times. It was interesting because the way they function, they're like soldiers in a way, they get triggered when they feel a disturbance and then they signal everyone and individually they're not that threatening, but as a swarm, they're terrifying. So I got stuff real early for that, some early visual effects, and I got a chance to already start putting some ideas together, did a ton of recording to get the wing element right. We did a bunch of flapping everything from leather jackets to canvases to heavy canvas bags to plastic elements. So we built up this whole library to get the movements in the wings, and then we started taking some shots at the vocals.

The swarm of Demo-Bats that nearly killed Steve and served as a pretty serious threat for the whole group of teens in the Upside Down had some ominous flapping sounds, but who could have guessed that they came from clothes and bags and plastic? Steve was more or less holding his own when he just had one of the bats attacking him, but that changed very quickly once the whole swarm arrived. Even if Steve hadn’t been in the Upside Down, it would have been clear that these were no common bats; according to Angelo Palazzo, that’s exactly what co-creators Matt and Ross Duffer were looking for. He said:

The Duffer brothers didn't want to have just traditional bats-type thing. They wanted it to be a little more vicious and things like that. So I took a shot at it, another editor Lee Gilmore did a great job [and] took a shot at it, and Craig Henighan. So the final result ended up being a hybrid of all three. The real standout elements – I had done a bunch of recordings of these. So the bats have really aggressive fluttery movements, like chittery kind of movements to their mouths. And so I had noticed that my closet door had, when I slid it back and forth, it had this shaky, high-pitched squeak to it, like chittery sound. I was like, 'Oh, man, that would be kind of cool.' Craig and I were talking about this. So we recorded these closet door slides and squeaks. Then we would just go through this process of manipulating these sounds and pitching them up higher and building out a library of these vocal sounds.

It’s probably pretty safe to say that most viewers weren’t thinking about squeaking doors when it came to the Demo-Bats attacking Steve, or when the other three teens arrived and they had to join forces to hold them off long enough to make an escape. Who could have guessed that the sounds for the bats not only didn’t come from any kind of real-life creature, but instead came from a door opening and shutting? The lead sound effects editor went on to share another unexpected source for a Demo-Bat sound, as he continued:

It's interesting because with sound design, you can kind of source your elements almost anywhere. The way I look at it is I tried to think of like, what else makes sounds like that or what else moves like that? And so it could be something like your closet door making these fluttering sounds that work great. Another thing we did is we recorded a cappuccino maker when you crank it and you foam the milk and [it] makes this high-pitched screaming sound. So we did all these recordings where we would manipulate the milk and different volumes, and it would create these really aggressive vocal sounds. So that combined with the closet, and we probably brought in some other elements I'm not remembering, but those were the core of the bats. It was a lot of fun making those.

Steve probably could have used a good cup of joe after barely surviving the swarm of Upside Down bats, but nobody in that group was thinking of coffee when they arrived through Watergate! Steve’s attack was undoubtedly one of the scariest – if not the absolutely scariest – sequences of Season 4 that didn’t involve Vecna, so the closet sounds plus cappuccino machine were both unexpected and very effective in creating the sound for the bats.

Honestly, kudos to Joe Keery, Natalia Dyer, Maya Hawke, and Joseph Quinn (whose Eddie is one of the standout newcomers of Season 4) for pulling off their terrified performances the scene without being able to see or hear the Demo-Bats in the same way that viewers would be able to with the release of Vol. 1. The bats attacking Steve was a doozy of a cliffhanger for the end of Episode 6, so viewers can be thankful that there was still one more episode of Season 4’s first volume to reveal his fate. The group isn’t out of danger from the bats just yet, with both Steve and Nancy still in the Upside Down at the end of Vol. 1, so only time – and Vol. 2 – will tell Netflix subscribers if and how they make it out. 

Whatever happens, the characters can only hope that those bats don’t follow the example of the Demogorgon and Demodogs and escape through a gate up to Hawkins! Find out what’s next when Vol. 2 of Stranger Things Season 4 releases on Friday, July 1 on Netflix. In the meantime, check out our breakdown of Vecna’s origin story as well as some of the big Stranger Things questions that still need answers. If Vol. 2 follows Stranger Things’ usual pattern of starting to bring storylines together in the final episodes of a season, then maybe the characters will start coming together despite all of the distance early on

Laura Hurley
Senior Content Producer

Laura turned a lifelong love of television into a valid reason to write and think about TV on a daily basis. She's not a doctor, lawyer, or detective, but watches a lot of them in primetime. Resident of One Chicago, the galaxy far, far away, and Northeast Ohio. Will not time travel and can cite multiple TV shows to explain why. She does, however, want to believe that she can sneak references to The X-Files into daily conversation (and author bios).