Do we only hear sounds? Or can we also hear silence? These questions are the subject of a centuries-old philosophical debate between two camps: the perceptual view (we literally hear silence), and the cognitive view (we only judge or infer silence). New research from Johns Hopkins University shows that silences can ‘substitute’ for sounds in event-based auditory illusions.
Goh et al. show that silences can substitute for sounds in three prominent auditory illusions caused by event representation. Image credit: Finmiki.
“We typically think of our sense of hearing as being concerned with sounds,” said Rui Zhe Goh, a graduate student at Johns Hopkins University.
“But silence, whatever it is, is not a sound — it’s the absence of sound.”
“Surprisingly, what our work suggests is that nothing is also something you can hear.”
“Philosophers have long debated whether silence is something we can literally perceive, but there hasn’t been a scientific study aimed directly at this question,” said Dr. Chaz Firestone, a researcher at Johns Hopkins University.
“Our approach was to ask whether our brains treat silences the way they treat sounds.”
“If you can get the same illusions with silences as you get with sounds, then that may be evidence that we literally hear silence after all.”
Like optical illusions that trick what people see, auditory illusions can make people hear periods of time as being longer or shorter than they actually are.
One example is known as the one-is-more illusion, where one long beep seems longer than two short consecutive beeps even when the two sequences are equally long.
In tests involving 1,000 participants, the study authors swapped the sounds in the one-is-more illusion with moments of silence, re-working the auditory illusion into what they dubbed the one-silence-is-more illusion.
They found the same results: people thought one long moment of silence was longer than two short moments of silence. Other silence illusions yielded the same outcomes as sound illusions.
The participants were asked to listen to soundscapes that simulated the din of busy restaurants, markets, and train stations.
They then listened for periods within those audio tracks when all sound stopped abruptly, creating brief silences.
The idea wasn’t simply that these silences made people experience illusions.
It was that the same illusions that scientists thought could only be triggered with sounds worked just as well when the sounds were replaced by silences.
“There’s at least one thing that we hear that isn’t a sound, and that’s the silence that happens when sounds go away,” said Johns Hopkins University’s Professor Ian Phillips.
“The kinds of illusions and effects that look like they are unique to the auditory processing of a sound, we also get them with silences, suggesting we really do hear absences of sound too.”
The findings establish a new way to study the perception of absence.
“We plan to keep exploring the extent to which people hear silence, including whether we hear silences that are not preceded by sound,” the scientists said.
“We also plan to investigate visual disappearances and other examples of things people can perceive as being absent.”
The study was published in the Proceedings of the National Academy of Sciences.
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Rui Zhe Goh et al. 2023. The perception of silence. PNAS 120 (29): e2301463120; doi: 10.1073/pnas.2301463120
Source : Breaking Science News