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Those long, sustained tones have been amping up the tension in movies since the early 1930s.

Wall Professor of Music Neil Lerner recently appeared in a Quartz.com video about the subtle -- and sometimes not-so-subtle -- audio cue.

“It’s the sound of dread,” Lerner told Adam Epstein, a Quartz reporter. “And that’s something that I think triggers fear in all kinds of creatures.”

According to Lerner, a musicologist who co-edited the book “Music in the Horror Film: Listening to Fear,” the 1931 film “Dr. Jekyll & Mr. Hyde” was the first to use the drone to trigger unease.

Today, it’s everywhere; popping up in dramas like “The Social Network” or even last week’s episode of “Game of Thrones.”

The “drone of death” can vary in tone and volume -- low, high, quiet or deafening -- but it has the same effect on viewers.

“Drones build up tension in their unwavering qualities,” Lerner said, “that reaction of unease; that’s what it’s there to do.”