Bilinguals hear sounds differently based on the language they think they’re listening to, new study shows

When is a “p” really a “p” or a “b” really a “b”? According to a new Concordia study, it depends on how you hear it and, if you are bilingual, the language you’re listening to.

In a paper published in the journal Cognition, researcher Krista Byers-Heinlein and her co-authors write that bilinguals perceive speech differently, depending on the language they think they are hearing.

A “p” sound, for instance, will be heard differently by a native English speaker than it will by a native French speaker. Same goes for the “b” sound. Pronunciation, even of a same syllable common to both languages, can vary, and that is where the research begins.

“French and English speakers hear the exact same sound differently,” says Byers-Heinlein, an associate professor of psychology in the Faculty of Arts and Science and Concordia University Research Chair in Bilingualism.

“An English speaker can hear some sounds as a ‘b’ but a French speaker would hear the exact same sound as a ‘p.’ That’s how language works. Our question was, what happens when you are bilingual, as so many people are?”

Byers-Heinlein recruited bilingual undergraduates from Concordia’s Department of Psychology for her study. The students were placed in front a computer and told they were going to hear a sound either in English or in French. The sound they heard was either “pah” or “bah” — syllables that were essentially meaningless without any further context.

“They could have been in English or in French. They could have been neither or both,” she says.

Switching ear filters

The researchers asked the students which sound they heard and they would click either a “p” sound or a “b” sound. The sounds would vary, from being very clearly a “b” or a “p” to ones that were intermediate.

The researchers discovered that the students would change their answers depending on which language they thought they were hearing. If they were told that they were hearing English, they were more likely to choose one sound; if they were told they were hearing French, they would be more inclined to pick the other. But the sound was the same in all cases.

The same was found of Spanish-English bilinguals as well, thanks to a concurrent study at the University of Arizona.

“We think that bilinguals have a bit of a different brain configuration when they are using English and when they are using French,” Byers-Heinlein explains. “It’s almost like there is a setting they can set to activate their English configuration and filter it through English ears versus a French configuration where they would filter it through French ears. And we think they can switch configurations very quickly.”

She notes that the subjects they tested were expertly bilingual, and they were able to switch “ears” with ease. She believes bilinguals develop this ability over time, and that this kind of switching wouldn’t be possible for less successful students who had only learned a second language relatively recently.

Byers-Heinlein says she is struck by the brain’s ability to so quickly identify and switch language filters.

“There’s nothing you need to do,” she says. “You do not need to make a special effort to listen in a certain way as you become proficient in your learned language. Your mind is automatically going to do it, which is pretty cool.”

The Natural Sciences and Engineering Research Council of Canada and the University of Arizona Graduate Diversity Fellowship supported the study. 

Read the full study, “How bilinguals perceive speech depends on which language they think they’re hearing.”