Andy Muschietti's IT has been scaring up a storm. Much like the clown jack-in-the-box Pennywise uses to scare one of the Losers in the final act of the movie, there are several keys to making the whole thing tick—and the film's music and sound design rank high among them. The score was composed by Benjamin Wallfisch (also responsible, just this year, for the scores to creep-fest A Cure for Wellness and Annabelle: Creation), and it works hand-in-hand with the slowly distorting sound design to make IT a worthy new entry in the horror genre.
Admittedly, some of IT's tricks are old hat. Creaky strings ramp up tension and abruptly loud cues are deployed for jump scares as the tale of a town haunted by a supernatural clown unfolds. The movie even opens with the hallmark of all scary movies: the faint sound of unidentified children singing in unison. But the piano melody that follows it is something new—diegetic music. As the doomed Georgie (Jackson Robert Scott) makes his way through the Denbrough house, we see his mother seated at a piano, picking out the tune we're hearing. This revelation has the effect of placing us directly in the action, making it all the more jarring when the music—and the safety net that it implies—drops away.
The trick works even more effectively when it comes to Stan's (Wyatt Oleff) fears. The object of his anxieties is a particularly creepy painting of a flautist in his father's office. He rights the painting, which hangs crooked on the wall, only to hear it fall to the floor as soon as he's turned his back. When he puts it back up, he discovers that the frame is suddenly empty, and there's the trill of a flute to signify the fear that's begun to set in. But when the camera pans around the room, it becomes apparent that that sound isn't just the score—the nightmarish woman has taken corporeal form, and is playing right behind Stan. Soon enough, the notes trail off, and there's a thunk as the flute is dropped to the floor. Once again, the safety net's gone. The chase is about to begin.
This isn't to take credit away from the score. Wallfisch's score is especially effective in how it echoes the scores of movies of the 80's, i.e. the time period in which the movie itself is set, and in particular of the movies of Amblin Entertainment (Jurassic Park, The Goonies, E.T., et al). The melodies themselves aren't particularly complicated, but the arrangements are heavily orchestral, in contrast to the more experimental and electronic-heavy scores that are popular today. That "classicism" works in concert with the few period-appropriate pop songs that get thrown into the mix (XTC's "Dear God," the Cure's "Six Different Ways," to name a couple). It all lends to a sense of nostalgia and comfort that makes the action's descent into madness all the more unsettling.
There's a slow warping in the film's sound design, too. Music box melodies sour and trail off in cues that don't make it clear as to whether what we're hearing is diegetic or not. So do circus calliope tunes, in the film's clearest indication that there's something wicked at play. They're traditionally instruments meant to indicate fun or innocence, particularly in the former case, and they work in a similar capacity as the score and the pop songs in turning our expectations against us.
Even Bill Skarsgård's performance as Pennywise follows in a similar vein. As the dancing clown, the cadence of his voice jumps up and down—it's high when he's trying to appeal to the kids, and falls lower and lower the more monstrous he becomes. And it's unsettling when it goes quickly from one to the other and back again, as it makes it harder to know what to expect from a monster that's already terrifying enough. Straight off the bat, he alters his way of speaking to coax Georgie into trusting him. It's only once the need for subtlety dissipates that his delivery goes full tilt.
Music and sound have always been key parts of effective horror, and IT serves up the aural scares. On the whole, the movie is most effective when it's grounded in the everyday details of the Loser's Club's lives. It's their adolescent anxieties and fears that are the most compelling part of the film, and the use of music and sound is successful in the same capacity. The diegetic cues draw viewers into the action, and the score works to lull the audience into a false sense of comfort and nostalgia before pulling the rug out from under their feet. In other words, Muschietti and Wallfisch use the same tactics that their dancing clown uses in luring Georgie to his doom, and if the box office records and critical reception are any indication, they're killing it.
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