The 14-month-old girl who can hear for the first time

Ava Pearson, 14 months old, can listen to bedtime stories and jiggle about to music thanks to the life-changing operation.

She is even starting to speak after being given an implant in one ear when she was nine months old and a second one in the other ear three months later.

Ava's speech therapist says her language skills are now ahead of other children the same age.

Her mother, Lauren, 31, from Belsize Park, said: "One week after the operation she started dancing to music and then four weeks later she said her first word, 'mama', which was huge for me.

"I realised she could hear when she kept pushing the top of a toy which played music and she started swaying to the tune. I couldn't believe it. Previously a siren could have gone past and she wouldn't have reacted.

"When she started babbling it was amazing - before that she only made guttural noises that she could feel in her chest." Mrs Pearson, a book publisher, and her husband Chris, a 31-year-old finance manager, first realised Ava was deaf when she didn't react to routine hearing tests at the age of three weeks.

Mr Pearson said: "We were very upset and it was a complete shock - there was no history of deafness in the family.

"Lauren started scouring the internet and discovered cochlear implants. We knew if you have them young it is better for speech and language development."

The couple decided to pay to have the implants at the private Portland hospital in the West End.

The cost, plus a year of speech therapy at the hospital and back-up equipment, is almost £52,000 and is being paid out of the family's health insurance. Mr Pearson said: "We knew that time was of the essence and that it wouldn't be as fast on the NHS." Speech therapist Natalie Opitz, who works at the Portland, said: "Ava is the youngest baby I have seen have the operation in this country. This is a remarkable case but it could be the norm for all deaf children."

A spokeswoman for the Royal National Institute for Deaf people said children are typically given the implants on the NHS aged between one and three but waiting lists for the operation vary across the country. She added: "The RNID wants to see a national framework that gives equal access to all those who would benefit more from a cochlear implant than from hearing aids."

A cochlear implant is made up of a receiver, which is surgically implanted behind the ear with electrodes inserted into the cochlea. A speech processor is magnetically attached to the outside of the head and sends electrodes to the inner ear. These send a signal through the auditory nerve to the brain, where it is perceived as sound.

Ava's second implant allows her to tell the direction from which sound is coming.