A rolled R is a sound that many struggle to produce, but research suggests it evokes the same curious response in people the world over: an association with a jagged line.
While onomatopoeia describes words that sound like the noise they describe – such as “bang” – sound symbolism is a broader concept, in which sounds map on to a wider range of meanings, such as shape, texture or size.
One of the best known examples is the bouba/kiki effect, whereby people typically match the nonsense word “bouba” to a blobby shape and “kiki” to a spiky one.
Now researchers say they have found an association that appears even more widespread, revealing a rolled – or trilled – R sound is consistently matched with a jagged line.
“It’s the strongest case of sound symbolism [to date]. So your speech sounds, which are supposed to be arbitrary, have meaning,” said Dr Marcus Perlman from the University of Birmingham, the co-author of the study.
Writing in the Journal of the Acoustical Society of America, Perlman and colleagues reported how they analysed data from 903 online participants and 127 in-person participants. Overall, participants spoke 28 different languages including Zulu, Palikúr, English, Farsi, Spanish, Russian, Japanese and Mandarin Chinese.
To carry out the experiment, researchers presented each participant with images of a jagged line and a smooth line, and instructed participants to imagine moving their finger along the marks. Participants then were played two sounds – one of a trilled R and one of an L sound – and asked to match each sound to a line. In the online experiments, a choice was made after each sound, whereas during the in-person experiments, choices were made after both sounds had played.
The results revealed that, overall, participants matched the jagged line with the rolled R and the smooth line with the L sound in 88% of the online trials and 98% of in-person trials – higher rates than have been found for the bouba/kiki effect. Analysis of the online-only data revealed the associations held regardless of which sound was played first, but was stronger for the trilled R and jagged line.
And while some languages do not show evidence of the bouba/kiki effect, this was not the case for the new pair of sounds. “It was consistent across all the languages,” Perlman said.
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Perlman said previous research by the team that looked at a range of languages found words used to refer to rough textures were statistically far more likely than chance to have an R sound in them, and that, when plotted on a graph, the rapid rise and fall of intensity during a trilled R resembles the contours of a crinkle-cut crisp.
“This particular case of sound symbolism seems to have a big influence on vocabularies in different languages,” he said. “I think it shows that speech sounds are not just acoustic objects, but they also have a texture and a shape to them.”