All children, and not just those considered to be at high risk, should be screened for deafness as soon as they are born, researchers have said.

A team at Southampton Hospital's neonatal unit has monitored the impact of universal testing of new-born babies over the last ten years.

They found that up to half the babies born with hearing difficulties are not diagnosed properly, because they do not get tested at birth.

At present, just six hospitals in the country carry out universal screening of new-born babies.

Elsewhere, only babies with a family history of hearing loss, other risk factors such as a facial abnormality, and those in special care baby units are tested.

However, 90% of babies with hearing loss are born to parents whose hearing is normal.

Jane Crook has two sons, four-year-old Gareth and two-year-old Daniel, who were both born profoundly deaf.

But whereas Daniel was fitted with a hearing aid at seven weeks, Gareth's disability was not identified until he was 18 months old.

Mrs Crook says the delay in diagnosing Gareth has led to severe impairment in the development of his communication and academic skills.

She said: "Gareth's language is severely delayed. He has got a very low language level. Daniel is almost on an equal level with Gareth."

Andy Phillips, a member of the UK national steering group for neonatal hearing screening, said it would cost about �14m a year for universal screening to be introduced.

He said: "Children with hearing loss are being detected far too late, and the later a hearing aid is fitted the worse they do."

The way forward

The Royal National Institute for Deaf People issued a statement which said: "RNID firmly believes that universal screening of new-born babies is the way forward.

"Children learn listening and speaking skills from their first days onwards, therefore the earlier they are identified as having hearing loss the better in order to provide suitable hearing aids or cochlear implants, if required.

"It also means that appropriate support and guidance is given to the family as early as possible.

"This will prevent delays and problems in the child's development and education and will also improve the lives of the whole family."

A simple technique known as otoacoustic emission testing can be carried out within 48 hours of birth and does not disturb the baby.

It involves an instrument sending a sound into the baby's ear and measuring the level of returned sound which calculates the level of hearing function.

The more traditional method of measuring hearing loss, the distraction test, requires a baby to sit upright on the mother's lap, responding to sound without seeing the source, and therefore cannot be done before 8 months.

In addition, the distraction test fails to identify some children who have a hearing impairment.