We’re big fans “Mythbusters”. Adam Savage and Jamie Hyneman filmed a segment called “The Haunted Hum” during their “Fright Night” Halloween episode. The two test an urban legend that claims that there is frequency around 19 Hz that can produce feelings of discomfort, dread and, yes, even fear. But the thing is, 19 Hz is below the threshold of human hearing, so these feelings are produced without anyone being able to hear the note.
The Mythbusters recruited sound scientist Dr. Roger Schwenke from Meyer Sound to help test the myth, and Schwenke brought quite the setup to a remote area in Northern California. That setup? A group of nine Meyer Sound 11000-LFC low-frequency control element speakers that produce about 40,000 watts of power.
Here’s how it worked: a group of subjects were spread out among four cabins, one of which had the group of speakers behind it producing the alleged fear note.
“One cabin was subjected to infrasonic sound while the other control cabins had no sound,” Schwenke said. “Although the cabins were essentially identical, the idea was to ask the participants if one cabin seemed more eerie or frightening than the others.”
Schwenke also described the specifics of the set up.
“We used the U-shape to get the 1100-LFCs as close together as possible,” he said, “and to direct any higher overtones away from the cabin so we could get the infrasonic level as high as possible without anything being audible… We had to be careful with that level because, at around 95 dB, we started rattling the cabin walls. That would have been a dead giveaway.”
The episode aired on October 28, but in case you haven’t seen it yet, I won’t give away whether the myth was confirmed, busted or deed plausible. However, I do have Schwenke’s thoughts on the unheard note.
“I did feel a sense of unease,” he said. “You could tell when it was on even though you couldn’t hear anything. It was more of a whole-body, change-in-the-air sensation, an undefined ominous feeling.”
This isn’t the first time audio myths have been put to the test on “Mythbusters.” Previous episodes have tested whether a human voice can actually break glass, if sound can extinguish flames and if there is really something known as the “brown note.”
If you haven’t heard of that last one, we’re going to leave it to you to check out on your own time.