Can You Hear It? Scientists Prove People Can Hear Silence for First Time
Simon and Garfunkel may have got it right – there is such a thing as the sound of silence. Or, at least, we perceive silence just like we do sound, a study suggests. For centuries, philosophers have suggested human beings do not ‘hear’ silence.
Instead, we said they didn’t hear any noise, so we realized we must be in a silent place. But researchers have new evidence that the brain actively processes silence itself, which they say could explain why we pay so much attention to ‘an awkward pause in a conversation, a suspenseful gap between thunderclaps, or the hush at the end of a musical performance.’
The claim is based on seven experiments involving 1,000 people, which showed tricks on the mind, that work with sound also work with silence. As some amateur magicians and illusionists know, if you play someone one continuous electronic tone or two separate tones of the same total duration, their brain will trick them into thinking one tone lasts longer.
And in the new study, people also thought one continuous silence was longer than two separate ones, suggesting the brain processes absolute quiet in a similar way to sound. Dr Chaz Firestone, senior author of the study from Johns Hopkins University in the US, said: ‘One of the reasons that the phrase the sound of silence is so compelling is that it is paradoxical.
‘Silence is the absence of sound. But these results suggest we hear silence like we do a sound, so there really may be some truth in the phrase the sound of silence after all.’
The study, published in the journal Proceedings of the National Academy of Sciences, played the single and double silences to people amid background noise of either a train, busy restaurant, bustling market, playground or white noise.
People judged the single silence as longer than two separate silences when asked to compare, just as they do with sounds. The illusion also worked when people were asked to press a key for how long the silences lasted, as well as when they simply compared them.
The researchers established that it wasn’t the surprise of the two silences being broken up by noise skewing people’s judgment by repeating the experiment with a chirping bird noise during the long silence. They also repeatedly found two electronic tones that were judged to have had a larger gap between them when played in silence which came between other sounds.
This was particularly the case when that silence came between other sounds – suggesting people’s brains actively perceive silence. Because, in real life, everyday sounds are cacophony and there is rarely total silence, the researchers judged how people reacted when an individual noise went silent.
Playing a high-pitched organ tone and a low rumbling engine at the same time, one of these sounds would go quiet several times. When the sound which had not previously dropped out was removed, people judged it as having gone silent for longer than when it was the expected sound that disappeared.
The array of audio illusions shows just how hardwired we are to perceive silence – the researchers conclude. Co-author Professor Ian Phillips, from Johns Hopkins University, said: ‘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.’
