How the movie Jaws inspired the creepy Friday the 13th "ki ki ki, ma, ma, ma" sound effect

In the 1980 classic splatterpunk film Friday the 13th, the eerie musical motif that haunts the film's tense moments was as crucial to the atmosphere as the suspenseful plot itself. Yet, the killer, Mrs. Voorhees, doesn't appear until the final scenes, leaving composer Harry Manfredini with the challenge of musically evoking her presence long before she steps into the frame. For inspiration, Manfredini turned to Jaws, Steven Spielberg's 1975 blockbuster, where John Williams' iconic score signaled the shark's unseen menace for much of the film.

One brilliant technique in Jaws was how Williams' music filled in for the shark's absence, using an ominous motif to cue the audience to its lurking danger. Manfredini said he wanted to achieve a similar effect for Friday the 13th. While listening to Polish composer Krzysztof Penderecki, known for his intense, dissonant choral music, Manfredini found the inspiration he needed—a chorus with "striking pronunciations" that would lead to his own chilling signature sound. Listen below.

"If you remember the movie, there's a scene towards the end where there's a close-up on Mrs Voorhees' mouth," Manfredini explained in a Slasherama interview. "It goes between the sound of Jason saying, 'Kill her mommy!', then the mother's voice, and back and forth. So I got the idea of taking the 'ki' from 'kill' and the 'ma' from 'mommy', but spoke them very harshly, distinctly and rhythmically into a microphone and run them through this '70s echo thing. It came up as you hear it today! So every time there was the perspective of the stalker, I put that into the score."

Recorded in a friend's basement, Manfredini's score was completed in just a few weeks, yet it has consistently creeped viewers out for nearly 50 years.

"Everybody thinks it's 'cha, cha, cha,'" Manfredini has said. "I'm like, 'Cha, cha, cha'? What are you talking about?"