Silence Is a 'Sound' You Hear, Study Suggests

An anonymous reader quotes a report from the New York Times: The hush at the end of the musical performance. The pause in a dramatic speech. The muted moment when you turn off the car. What is it that we hear when we hear nothing at all? Are we detecting silence? Or are we just hearing nothing and interpreting that absence as silence? The "Sound of Silence" is a philosophical question that made for one of Simon & Garfunkel's most enduring songs, but it's also a subject that can be tested by psychologists. In a paper published Monday in the Proceedings of the National Academy of Sciences, researchers used a series of sonic illusions to show that people perceive silences much as they hear sounds. While the study offers no insight into how our brains might be processing silence, the results suggest that people perceive silence as its own type of "sound," not just as a gap between noises. The researchers tested people recruited online with a series of sound illusions. The first test compared a single longer sound with two shorter sounds. The two shorter sounds together added up to the same amount of time as the longer sound. But when people listened to them, they perceived the single sound as lasting longer. To apply that illusion to silence, [Rui Zhe Goh, a graduate student in cognitive science and philosophy at Johns Hopkins University] and colleagues inverted the test. The scientists used sounds of restaurants, busy marketplaces, trains or playgrounds, and inserted chunks of silence for participants to compare. The researchers supposed that if people perceive silences as their own type of sound, then silences should be subject to the same illusion as the sounds. One long silence should be perceived as longer than the total of two shorter silences. But if people perceive silence as a lack of sound, the illusion might not exist. Other tests placed silence in different contexts to produce more sonic illusions. In every case they tested, listeners perceived the illusion of a period of silence being longer just as they would have perceived an illusion of a longer sound. [...] Although the researchers did not study how people's brains responded to silence, Mr. Goh suggested that existing research supported the idea that some neurons and neural processes were involved in the perception of silence. And knowing that we do perceive silence makes silence that much, er, louder: "Silence is a real experience," Mr. Goh said. Maybe we'll all pay more attention to moments of quiet once we know we can hear the "sounds" of silence.

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