Silence has been described as simply the absence of sound — like the end of a song just before the next one starts or the lull in a conversation. For a long time, it’s been considered the placeholder of sound — or at least as we understood it.

Scientists continue to debate what happens in the brain to tell us there is silence. When there is no sound to hear, do our brains simply infer and tell us this must be silence or do we directly perceive silence like we do sound?

A study published in the Proceedings of the National Academy of Sciences was one that Simon & Garfunkel would’ve been proud of — researchers sought to answer the question, “What is the sound of silence?” Evidence from the study shows that our ears perceive silence like they do sound, making it more interesting than it appears.

The sound of silence

To test their theory, researchers from the study tested to see if humans reacted the same to sound as they did to silence.

Sarah Hargus Ferguson, an associate professor of communication sciences and disorders at the University of Utah, told the Deseret News that the study was “mind-blowing” because it used similar tools used in studies on sound.

There’s an illusion that happens with sound, where one long sound can seem a lot longer than if the same amount of sound was broken into several pieces — this is called the one-is-more illusion. Researchers of the study hoped to compare sound and silence by seeing if silence evoked the same reaction from participants.

Study participants listened to a timed amount of ambient noise, like people talking, dishes clinking in a restaurant or a crowded playground, with timed moments of silence. The results clearly showed that the uninterrupted silence was seen as longer than the broken-up sections of silence.

Even Rui Zhe Goh — a graduate student of cognitive science and philosophy at Johns Hopkins University, who made the audio for the study — was surprised at the effectiveness of the illusion when he tried it himself, he told The New York Times.

“Silence is a real experience,” Goh told the Times.

Chaz Firestone, a co-author of the study, told the Times that whether the illusion is done with sound or silence, “you get the same effect.”

(Still a little skeptical of this particular illusion? Demos of the noise can be found on the study’s webpage, where listeners can test the illusion out for themselves.)

If silence mimics this same attribute of sound, there’s a viable case that silence has a lot more to it than we thought.

While the study didn’t measure what happens in the brain when people hear silence, Ferguson said “that our brain and mind are doing the kind of calculations they do on sound” when we hear silence.

“We don’t just turn off our brains in silence,” she told the Deseret News.

Perspective: The noise pollution we inflict on ourselves
Why silence really is golden — for your health