The Sound of Silence: New Work Suggests ‘Nothing is Also Something You Can Hear’
The sound of silence literally can be heard, concludes a new study published today in Proceedings of the National Academy of Sciences.
A team of philosophers and psychologists has concluded that silence, although not deafening, is something that can be audibly perceived. Through the use of auditory illusions, they have uncovered how moments of silence distort people’s perception of time.
The team’s findings address a longstanding philosophical debate regarding whether humans can hear more than just sounds. Lead author Rui Zhe Goh, a graduate student in philosophy and psychology at Johns Hopkins University, emphasized that while our sense of hearing is typically associated with sounds, silence, despite being the absence of sound, is not merely an absence.
Goh said, “Surprisingly, what our work suggests is that nothing is also something you can hear.”
The research, set to be published in the Proceedings of the National Academy of Sciences, involved adapting well-known auditory illusions by replacing the sounds with moments of silence. For instance, one illusion made a sound appear significantly longer than its actual duration. In the team’s new silence-based illusion, an equivalent period of silence also appeared longer than its real duration.
According to the researchers, the fact that silence-based illusions yielded identical results to their sound-based counterparts indicates that people perceive silence in the same way they perceive sounds.
Chaz Firestone, an Assistant Professor of Psychological and Brain Sciences and the director of the Johns Hopkins Perception & Mind Laboratory, noted, “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.
“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.”
Similar to optical illusions that deceive visual perception, auditory illusions can manipulate the perception of time, making certain periods appear longer or shorter than they actually are. For example, the “one-is-more illusion” makes a single prolonged beep seem longer than two short consecutive beeps, even if the two sequences are equally long.
In their tests involving 1,000 participants, the team replaced the sounds in the one-is-more illusion with moments of silence, creating what they referred to as the one-silence-is-more illusion. They discovered that people had the same perception: One long moment of silence appeared longer than two short moments of silence. Other silence illusions produced similar outcomes to sound illusions.
During the experiments, participants listened to simulated soundscapes that replicated the bustling atmosphere of restaurants, markets, and train stations. They were then asked to identify periods within these audio tracks when all sounds abruptly ceased, resulting in brief silences. The researchers clarified that their intention was not solely to make people experience illusions through these silences. Rather, they aimed to demonstrate that the same illusions previously believed to only occur with sounds were equally effective when the sounds were replaced by silences.
Co-author Ian Phillips, a Bloomberg Distinguished Professor of Philosophy and Psychological and Brain Sciences, remarked, “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.
“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.”
These findings provide a new avenue for studying the perception of absence, according to the research team.
Moving forward, the researchers intend to further explore the extent to which people perceive silence, including whether we perceive silences that are not preceded by sound. They also plan to investigate visual disappearances and other instances where individuals can perceive the absence of something.
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