Bilingual People Use Different Sound Systems
May 21, 2013

Bilingual People Use Different ‘Sound Systems’ To Switch Languages

Brett Smith for - Your Universe Online

New research from the University of Arizona shows that bilingual individuals switch between two different ℠sound systems´ in their brain when alternating between languages.

“A lot of research has shown that bilinguals are pretty good at accommodating speech variation across languages, but there´s been a debate as to how,” explained Kalim Gonzales, a doctoral student at the University of Arizona and lead author of the study, which will appear in a future edition of the journal“¯Psychological Science.

“There are two views: One is that bilinguals have different processing modes for their two languages — they have a mode for processing speech in one language and then a mode for processing speech in the other language,” Gonzales said. “Another view is that bilinguals just adjust to speech variation by recalibrating to the unique acoustic properties of each language.”

The new study supports the first view — that bilinguals have a separate sound processing method for each language they know. For example, the ℠pa´ and ℠ba´ sounds both exist in English and Spanish. However, when pronouncing ℠ba,´ English speakers learn to vibrate their vocal chords as they open their lips, while Spanish speakers vibrate their vocal chords slightly before saying ℠pa.´ As a result, English-only speakers might confuse the ℠ba´ and ℠pa´ sounds when made by a native Spanish speaker.

"When most people think about differences between languages, they think they use different words and they have different grammars, but at their base languages use different sounds," said study co-author Andrew Lotto, UA associate professor of“¯speech, language and hearing sciences.

In the study, the researchers recruited 32 Spanish-English bilingual speakers who had learned both languages before the age of 8. The participants were divided into two groups: One group was told they would be hearing little-used Spanish words, while the other group was told they would be hearing uncommon English words.

The researchers played both groups audio recordings of the same two fake words — “bafri” and “pafri.” They then asked the participants to identify whether the words they heard began with a ℠ba´ or a ℠pa´ sound. Additionally, for the group that was told they were hearing Spanish, the ℠r´ in each word was said with a Spanish pronunciation.

The researchers found that participants perceived the ℠ba´ and ℠pa´ sounds differently based on context — whether it was with the Spanish pronunciation of ℠r´ or the English pronunciation of ℠r.´

"What this showed is that when you put people in English mode, they actually would act like English speakers, and then if you put them in Spanish mode, they would switch to acting like Spanish speakers," Lotto said. "These bilinguals, hearing the exact same 'ba's and 'pa's would label them differently depending on the context."

When the study was repeated with 32 English-only speakers, participants labeled the 'ba' and 'pa' sounds the same way despite any language or pronunciation context.

"Up until this point we haven't had a good answer to whether bilinguals actually learn two different codes — so a 'ba-pa' English code and a 'ba-pa' Spanish code — or whether they learn something that's sort of in the middle," Lotto said. "This is one of the first clear demonstrations that bilinguals really do have two different sounds systems and that they can switch between one language and the other and then use that sound system."