Examining the Phenomenon of Silence: Insights into Perception

Johns Hopkins University

Silence may not be deafening, but it is something that can literally be heard, concludes a team of philosophers and psychologists who used auditory illusions to reveal how moments of silence distort people’s perception of time.

The findings address the debate of whether people can hear more than sounds, which has intrigued philosophers for centuries.

Summary

Auditory perception is traditionally conceived as the perception of sounds : a friend’s voice, thunder, a minor chord. However, everyday life also seems to present us with experiences characterized by the absence of sound : a moment of silence, an interval between thunder, the silence after a musical performance. In these cases, do we listen positively to the silence? Or do we simply not listen, and simply judge or infer that it is silent? This long-standing question remains controversial in both philosophy and the science of perception, with prominent theories holding that sounds are the only objects of auditory experience and therefore our encounter with silence is cognitive, not perceptive. However, this debate has remained largely theoretical, without key empirical evidence.

Here we present an empirical approach to this theoretical dispute, presenting experimental evidence that silence can be genuinely perceived (not just cognitively inferred). We asked whether silences can “substitute” for sounds in event-based auditory illusions, empirical signatures of auditory event representation in which auditory events distort perceived duration. Seven experiments introduce three "silence illusions" : the one-silence-is-more illusion, the silence-based warp, and the strange silence illusion, each adapted from a prominent perceptual illusion previously thought to arise only from sounds. Subjects were immersed in environmental noise interrupted by silences structurally identical to the sounds of the original illusions. In all cases, the silences caused temporal distortions perfectly analogous to the illusions produced by sounds.

Our results suggest that silence is actually heard , not simply inferred, introducing a general approach to studying the perception of absence. The silences caused temporal distortions perfectly analogous to the illusions produced by sounds.

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"We usually think that our sense of hearing is related to sounds. But silence, whatever it is, is not a sound, it is the absence of sound," said lead author Rui Zhe Goh, a graduate student in philosophy. and philosophy from Johns Hopkins University. psychology. "Surprisingly, what our work suggests is that ’nothing’ is also something you can hear."

The research has been published in Proceedings of the National Academy of Sciences .

The team adapted well-known auditory illusions to create versions in which the sounds of the original illusions were replaced by moments of silence. For example, an illusion made a sound appear much longer than it really was. In the new illusion based on team silence, an equivalent moment of silence also seemed longer than it actually was.

In this experiment, researchers at Johns Hopkins University replaced silences with sounds in a well-known auditory illusion. The idea was to see if people’s brains treat silences the same way they treat sounds. Credit: Johns Hopkins University

The fact that these silence-based illusions produced exactly the same results as their sound-based counterparts suggests that people hear silence just as they hear sounds, the researchers said.

"Philosophers have long debated whether silence is something we can literally perceive, but there has been no scientific study aimed directly at this question," said Chaz Firestone, assistant professor of Psychology and Brain Sciences who directs the Johns Hopkins Perception. & Mind. Laboratory. "Our approach was to ask whether our brains treat silences the same way they treat sounds. If you can get the same illusions with silences as with sounds, then that may be evidence that we literally hear silence after all."

Like optical illusions that fool what people see, auditory illusions can cause people to hear longer or shorter periods of time than they actually are. An example is known as the one-is-more illusion, where one long beep appears longer than two consecutive short beeps, even when the two sequences are equally long.

In tests involving 1,000 participants, the team swapped sounds in the one-is-more illusion with moments of silence, transforming the auditory illusion into what they called the one-silence-is-more illusion . They found the same results. People thought that one long moment of silence was longer than two short moments of silence. Other silence illusions produced the same results as sound illusions.

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 abruptly stopped, creating brief silences. The idea wasn’t simply that these silences would cause people to experience illusions, the researchers said. It was that the same illusions that scientists thought could only be triggered by sounds worked just as well when the sounds were replaced by silences.

"There is at least one thing we hear that is not a sound, and that is the silence that occurs when sounds disappear," said co-author Ian Phillips, Bloomberg Distinguished Professor of Philosophy and Psychological and Brain Sciences. "The types of illusions and effects that seem to be unique to auditory processing of a sound, we also get with silences, suggesting that we really hear absences of sound as well."

The findings establish a new way to study the perception of absence , the team said. The researchers plan to continue exploring the extent to which people listen to silence, even if we hear silences that are not preceded by a sound. They also plan to investigate visual disappearances and other examples of things that people may perceive as missing.