The New findings address a debate over whether humans can hear more than sounds that has puzzled philosophers for centuries. The research is ready for publication in the Proceedings of the National Academy of Sciences.
Lead author Rui Zhe Goh, a graduate student in philosophy and psychology at Johns Hopkins University says “We usually think of our hearing as being about sounds. But silence, whatever it is, is not sound it’s the absence of sound and surprisingly, our work suggests that nothing is also something you can hear.”
The team modified well-known auditory illusions to create versions in which the sounds of the original illusions were replaced by moments of silence. For example, one illusion made the sound seem much longer than it actually was. In the new illusion based on the team’s silence, the equivalent moment of silence also appeared longer than it actually was.
The fact that these silence-based illusions produced exactly the same results as their sound-based counterparts suggests that people hear silence the same way they hear sounds, the researchers said.
Chaz Firestone, an assistant professor of psychology and brain sciences who directs the Johns Hopkins Perception & Mind Laboratory says “Philosophers have long debated whether silence is something we can literally perceive, but there is no scientific study that has directly addressed this question, our approach was to ask whether our brains treat silence the same way they treat sounds. If you can get the same illusions with silence as with sounds, then that may be evidence that we are literally hearing silence after all.”
Just as optical illusions deceive what people see, auditory illusions can make people hear periods of time that are longer or shorter than they actually are. One example is known as the one-is-more illusion, where one long beep appears longer than two short consecutive beeps, even though both sequences are the same length.
In tests involving 1,000 participants, the team swapped the sounds in the one-is-more illusion for moments of silence and redesigned the auditory illusion for 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 sound scenes that simulated the noise of busy restaurants, markets, and train stations. They then listened within these audio tracks for a period of time when all sound suddenly stopped, creating a brief silence.
The idea wasn’t just that these silences caused people to experience illusions, the researchers said. The point was that the same illusions that scientists thought could only be triggered by sounds worked just as well when the sounds were replaced with silence.
The kinds of illusions and effects that seem to be unique to auditory processing of sound are also obtained using silence, suggesting that we actually hear the absence of sound.
The findings represent a new way to study absence perception
The researchers plan to continue investigating the extent to which humans hear silence, including whether we hear silence that is not preceded by sound. They also plan to explore fading vision and other examples of things that people can perceive as absent.
Reference: https://www.sciencedaily.com/releases/2023/07/230710180451.htm
