Since 1989 cochlear implants have been given to 120 deaf children at Queen’s Medical centre in Nottingham, all of whom still wear them. Based on its success to date, the centre estimates that within five years of surgery more than 90 per cent of deaf children under five will be able to use spoken language as their first means of communication.

The results lend weight to comments by Lord Ashley of Stoke, a champion of deaf people, who last week extolled the benefits of the operation that restored his hearing after 24 years of profound deafness.

The implant, sometimes called a “bionic ear”, provides electrical signals that stimulate the hearing nerves directly, bypassing the damaged cochlea or inner ear. A traditional hearing aid simply amplifies sound.

In a speech to the Royal Society of Medicine, Lord Ashley condemned as “nonsense” the view of some critics that a decision on surgery should be left until the child is old enough to make up its own mind.

Mistrust of cochlear implants has been voiced by the British Deaf Association, which represents people who were born deaf. According to BDA spokesman David Nicholson, a cochlear implant “can be an aid to communication but it does not make deaf children into hearing people.

“We are not convinced that providing deaf children from birth with the implant is generally effective to the point that they are fully able to communicate in the hearing world. That is still to be proven.”

It took about 18 months for deaf children to learn to make sense of the auditory information they received from an implant, a period during which their language development was “in limbo”, Mr Nicholson argued. “If you have a child who is two years old, or whatever, those years are absolutely vital in the development of language.”

Some BDA members feared a return to the 1960s when deaf children equipped with inadequate hearing aids were sent to mainstream schools: “It caused a lot of psychological harm, and we are concerned that the same type of mistakes are being made with cochlear-implanted children,” he said.

The association was also concerned that cultural issues were “being sidelined in the drive to normalisation, to bring deaf children into the hearing world”. Many profoundly deaf children were at ease with deaf culture, the company of their deaf peers and communication by sign language.

“We advocate that parents of deaf children should be given a choice of educational settings between schools that prefer sign language and those that mix different modes of communication. The support offered to deaf people should be available whether they have a cochlear implant or not.”

But Sue Archbold, co-ordinator of the paediatric cochlear implant programme at Nottingham, defends the operation: “Our children choose to wear these devices. A lot of children leave them on in bed at night so they can hear their parents downstairs.”

Surgery was not suitable for all children, particularly those with residual hearing or those with other handicaps. It only took place after extensive auditory tests and consultations with parents.

However, early diagnosis was vital. After the age of five, implantation was likely to be less beneficial.

Spoken language development may be slow at first but - contrary to the view of the BDA - implanted children can catch up with their hearing peer group within a few years, said Mrs Archbold. “We are more than happy for children to be in a total communication setting where they communicate by using sign language and spoken language. But we find that as they develop a spoken language, it becomes more effective for them.”

She also disputed the view that implantation was not suitable for congenitally-deaf children: “If the child is implanted under five they acquire spoken language in a very natural way. In many ways it is easier for a congenitally deaf child because they have not got any preconceived ideas. ”

However, a follow-up programme to provide educational support was essential. Nottingham had developed an outreach programme to visit schools and teachers working with deaf children.

“We are working very closely with the British Association of Deaf Teachers to ensure teachers have the necessary skills to work with children with implants and look after the system.”

The National Deaf Children’s Society also believes that cochlear implants can benefit pre-lingually, as well as post-lingually, deaf children. It provides information about the practical and ethical issues to help parents choose.

But chief executive Susan Daniels is aware that the need to carry out surgery at an early age can put families under pressure. “Some families come to us having read that implants should be given when the child is very young, and they are not ready to make that decision.”

The society wants medical teams to develop clear criteria about which children are suitable for implants, and says parents must be told about the potential outcomes.

“Children should understand that implants do not restore hearing in a way that a hearing person would understand it. What they can do is give an awareness of environmental noise, like a car passing. Some children may be able to hear speech sounds without lip reading but they are in the minority.”