London, May 11: Babies who hear foreign speech in their first nine months tend to pick up languages faster in school or as adults, a new research has found.
But those who hear only English as babies are left unable to distinguish between subtly different sounds not used in their native language.
The findings will provide an excuse for British tourists who have struggled with foreign languages while travelling.
Psychologists at Bristol University found that the developing brain undergoes a period of "programming" in infancy, which sets up for life its ability to recognise key sounds in whatever will become its native language.
This process helps the brain make sense of speech by filtering out sounds not used in the native language, but also makes it harder to recognise unfamiliar sounds from foreign languages.
Crucially, babies exposed to multiple languages during their first few months retain the ability to recognise sounds from all the languages they hear.
English speakers, for example, usually only recognise one "k" sound, but Irish Gaelic, Russian and Turkish speakers can differentiate between hard and soft "k" sounds, which produce different meanings in those languages.
Similarly, English speakers often struggle to hear the difference between the French "u" sounds in "loup" and "lu" despite the words having quite different meanings - wolf and the past participle of read.
"When a baby is born, it has the capacity to distinguish every type of speech sound. Even if the parents are English, the baby has the capacity to distinguish Greek and Chinese vowel sounds," the Telegraph quoted Dr Nina Kazanina, an expert in linguistic psychology at Bristol, as saying.
"By six months an infant can only recognise vowels from its native language, and within another two or three months the same happens to consonant sounds. So within around nine to 10 months, a baby's universal language ability is reduced to its native language.
"This happens because the brain is trying to make sense of sounds used in speech in the context of the native language, and so applies a kind of filter to help make it easier to understand words," she added.
She believes this explains why English speakers struggle to learn French compared with Italian and Spanish speakers, who have more similar sounds in their native tongues.
But the effect can work in the opposite direction too. English speakers find it far easier to pronounce Russian vowels than Russians do English vowels because English has more vowel sounds, so those who speak it have a broader repertoire.