Infants who hear foreign speech in their first nine months of life find it easier to pick up languages in school later, 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 study added.

Psychologists at Bristol University found that 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, the researchers said.

Babies exposed to multiple languages during their first few months retained the ability to recognise sounds from all the languages they hear, they added.

English speakers, for example, usually only recognised one 'k' sound, but Irish Gaelic, Russian and Turkish speakers could differentiate between hard and soft 'k' sounds, which produce different meanings in those languages, the study explained.

Dr Nina Kazanina, an expert in linguistic psychology at Bristol, said, ''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.'' ''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,'' she added.

''So within around nine to 10 months, a baby's universal language ability is reduced to its native language,'' Dr Kazanina told the Daily Telegraph.

''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 explained.

A separate study at the University of Washington has shown that speaking different languages to babies in their early lives can be crucial in helping them learn new languages later in life.

Researchers found that babies who were spoken to in Chinese for just one hour a week found it easier to recognise Chinese speech when they were older.