Some studies have shown that the ability for children to learn a second language starts fading as early as their first years.
However, according to a recent study, the brains of babies raised in a bilingual home show longer periods of flexibility to learn different languages than other children.
Researchers from this study measure the brain activity throughout a child’s first years of life and relate it to the language exposure and speaking ability. This study shows babies who have only been exposed to one language start losing the ability to distinguish sounds from a foreign language at eight- to 10 months old, while babies who have been constantly exposed to more than one language start losing this ability between 10 and 12 months old.
Early exposure to more than one language is vital in these cases. For example, if bilingual children are more exposed to English at home, including relatives and friends, these children will subsequently produce more words in English. The same pattern goes for other languages. The researchers say the best way for a child to learn more than one language is through social interactions and constant exposure to the language.
A great number of Utah households are bilingual due to immigration, people who have returned from serving LDS missions in different countries, among others, and some of these families decide to only speak the foreign language at home. However, language instructors say using the “one parent, one language” system works better, but parents need to be very consistent as they use it.