Hulu’s new original series Castle Rock is based on the universe of Stephen King. The Maine town of Castle Rock has been the setting of several of King’s stories and there are tons of Easter eggs and references to his works in the show. But the story in the Castle Rock series is original — not an adaptation of King’s works. The series creators, Sam Shaw and Dustin Thomason, are credited as writers on all 10 episodes and so far, they’re doing an excellent job of it. Even King himself said in a tweet that Castle Rock shouldn’t be watched just for the Easter eggs, and instead, to “…enjoy it on its own terms. The cast is incandescent and they support a story worth telling.”

The show is successful in other ways, particularly the sound, which is truly a part of the storytelling. Sometimes fact is stranger than fiction, and in terms of sound, sometimes realistic sounds are stranger than synthetic ones. Castle Rock‘s sound is a blend of natural elements that feel unnatural at times, like the mysterious sound that precedes Young Henry’s reappearance in Episode 1 — a sound that has the townspeople asking, “Do you hear it now?”

Leading the post sound team on the show is award-winning supervising sound editor Tim Kimmel of Formosa Group. Kimmel won an Emmy and has been nominated for four more for sound editing on HBO’s Game of Thrones — including this year for Season 7, Ep. 4 “The Spoils of War.” Here, Kimmel talks about the direction for sound on Castle Rock and how they created everything from practical and suspenseful to supernatural sounds.

What were the showrunners’ goals for sound on Castle Rock? How do you help them tell their story through sound?

Tim Kimmel (TK): Sound definitely plays an integral role in Castle Rock. We had discussions early on about specifics, namely the sound that young Alan Pangborn (Jeffrey Pierce) hears in the forest before he discovers Henry (Caleel Harris) in the very opening of the first episode. That sound, as you will see as time goes on, is important to the story. We had big discussions on what that sound was, what it means, and how it needs to transform and morph as the season goes on and we discover what that sound is. I don’t want to give too much away and spoil anything.

Sound is also used to help give the feeling of where we are. We had to create the proper ambience is of certain winter locations in Castle Rock, especially the Shawshank prison. There’s a grittiness to the prison — the prisoners and the doors and the isolated, unused block of the prison where we discover The Kid (Bill Skarsgård).

Going back to that sound that Pangborn hears out at the frozen lake, can you talk about what went into creating it? Without giving too much away, of course…

The goal was to create a sound that could be part of nature but there’s something not quite right about it.

TK: We spent a lot of time trying to find the sound they were looking for. I wanted to make sure that the sound didn’t become too musical so that it didn’t sound like score. The showrunners weren’t completely sure what they wanted. They explained to me where the sound shows up as the season progresses. So I created four or five options somewhat different from each other — just general sketches of ideas, and sent them to the showrunners. There was one option that they liked the most and there were elements of the other options that they liked, so I combined the two into a version that is what you hear and that first episode. It’s a little bit of a low tone and elements of it sound like whistling wind blowing in the winter but also there’s some low creature elements to it. There are some animal vocal elements but that doesn’t give away what it actually is; those are just elements that I used. The goal was to create a sound that could be part of nature but there’s something not quite right about it.

How does the sound evolve? What affects its evolution?

TK: It can be tailored to the listener’s experience or where they are when they are hearing it and how they’re hearing it. You’ll see pretty soon some definite variations on that sound and how it affects people.

In Episode 1 “Severance”, there are some really lovely places where the sound gets to tell the story. There’s no music or dialogue. One of those places is Warden Lacy’s suicide scene. After he drives up to the cliff, he turns off the radio and it’s just sound effects. How did you use sound to build the tension there, to make the scene uncomfortable for the audience?

TK: I love how it goes from full music to just nature sounds. We tried to create it nice and rich with nature, with distant birds. He’s out there by himself. There is nobody there and you wonder what he’s doing there. Then you hear a rustle in the bushes and a dog comes out and looks at him. There’s a nice little quiet moment of contemplation and then he jams the gas pedal and goes for it.

There are a lot of fun moments in there, playing with nature and designing exactly what we want you to hear. You try to hit the good solid details of tires screeching and rocks flying, hearing that car propel forward and that rope around his neck becoming taught. We hear it snap and the car goes airborne into the water. The fun thing about that scene is that we hit the car sounds really hard — all the engine and tires and rope, and when it becomes airborne you get a little break. You just hear the whir of the tires and a little bit of the engine before we get to the big splash into the water.

The fun details in there are the car going off of the cliff and the tires spinning and the engine stopping as the car slowly makes its way underwater. There’s the bubbling sound of the water going in and then the score slowly takes over.

They knew when they were writing the script what they wanted to hear on the sound side.

The show runners are very sound specific. I found that out before I even met them, when I started reading the scripts. They were very descriptive sound-wise in the scripts and many of these scenes had exactly what they were looking for. They knew when they were writing the script what they wanted to hear on the sound side. They heard in their heads what they wanted to do there and where they wanted to go with it, which was helpful for us. We had a good idea of what they wanted and once we started watching it and seeing what they did visually we were able to discuss really find details of what they liked.

The rope creaks, seat creaks, and steering wheel grabs… were those covered in Foley? Or, did you cut those in with effects?

TK: It was a little bit of both. The Foley definitely helped us out. I use an amazing Foley crew, Happy Feet Foley with Jeff and Dylan Wilhoit and Brett Voss. I’ve been working with them for quite a few years now. They did a lot of the seat creaks and the rope, and helped with the dirt and gravel flying as the tires started to spin. They helped with all those sounds tremendously.

The atmosphere inside Shawshank prison, how did you want that space to feel? How did you achieve that through sound?

They want to get the prison sounding as dirty as it can without drowning out the dialogue

TK: The showrunners Dustin and Sam wanted the prison to sound dirty. Some shows want a bit of prison sound as long as it doesn’t step on the dialogue but they wanted more than that. They want to get the prison sounding as dirty as it can without drowning out the dialogue, of course. They want to feel it’s a prison and not a nice prison. It needs to feel active.

We shot a lot of loop group for the prison, to add some good character to the people in there. There are a lot of doors slamming in the background and gate buzzes. There’s also a nice, low drone to keep this uneasy feeling going through the prison.

And for Cell Block F — the burned out, uninhabited part of the prison, how does that atmosphere compared to the main prison?

TK: You can’t hear any of the prisoners down there or the PA announcements. We wanted it to feel empty. There’s just a desolate little wind going through there like nobody has been in there for a long time. We wanted it to feel like that section had been empty for years and that no one has walked in there, until we discover the Warden’s footsteps. Then, the deeper that Dennis Zalewski (Noel Fisher) goes into there, the more haunting it got. We played with creaking metal and hums and low tones, to start to create a somewhat haunting atmosphere. We wanted to create a definite “we shouldn’t be going down here” type feeling.

The story cuts from past to present, and sometimes overlaps moments in the present. For example, Henry visits the site of the Warden’s death, Dennis watches the CCTV screens in the jail, and Molly explores her box of memorabilia from Henry’s disappearance. How do you use sound to help weave these moments together?

TK: There are some moments like that where the showrunners don’t want to feel the transition too much. For instance, you’re in the autumn in the present day then all of the sudden you slowly start to realize that it’s winter and in a different time. It slowly weaves into that and it builds but then you’re cut off and you realize that no, you’re right here in this moment. We drop the wind and the winter sounds and put us back in the present day in the autumn.

We play with wind a lot. What’s great about the way they shot it is that you see a lot of tree movement in the forest, and so you can hear the wind blowing through the leaves and branches creaking and bumping each other a bit.

In that scene that you are describing, Henry walks out to the cliff and you hear a little bit of water movement to remind you that he’s at the lake and the water isn’t frozen.