When a pregnant mother is asked if she would prefer a boy or a girl the response is pretty formulaic - "I don't mind as long as it's healthy." Which, put another way, means: "I don't mind as long as it's not impaired in any way." But what if the expectant mother or father actually preferred it if the baby wasn't "healthy", in the sense that we understand the word, but instead was profoundly deaf?

This is how Paula Garfield, artistic director of the London-based theatre company Deafinitely Theatre, felt when she was expecting her baby daughter, Molly. "When I was pregnant I did hope the baby would be deaf. Obviously, I would have loved a hearing baby equally, but inside, I really hoped she would be deaf like me."

For Garfield and her partner Tomato Lichy, an artist and writer, the diagnosis that Molly was profoundly deaf was a cause for joy rather than sadness. "When the doctor told us she was deaf I really wanted to smile, but I felt I shouldn't because the medical staff obviously thought deafness was a problem. Once we got home we celebrated though."

So, why? The answer, Lichy argues, lies in language. "Being deaf is not about being disabled, or medically incomplete - it's about being part of a linguistic minority. We're proud, not of the medical aspect of deafness, but of the language we use and the community we live in. We're delighted that that is something our daughter can share as she grows up."

Taking into account the widest spectrum of hearing impairment - from slightly hard of hearing to profoundly deaf - the Royal National Institute for the Deaf estimates that close to 9 million people in Britain have some degree of hearing loss. Most will be older people with age-related deafness: think of someone who turns the telly up loud or who says "you wot?" a lot. Around 55% of people over 60 have some degree of hearing loss compared to just 2% of young adults.

According to the Disability Rights Commission, somewhere between 30,000 and 70,000 deaf people use British Sign Language (BSL) as their first or preferred means of communication. Most of them will have either lost their hearing through illness such as meningitis in childhood, or, like Garfield and Lichy, have been born with congenital deafness to hearing parents (Garfield has a deaf twin sister; Lichy is the only deaf member of his family).

For the couple, it is very much Deaf with a capital D, denoting their identity within a cultural group, rather than a medical aggregate of people with less hearing than the majority. To them, deaf, like "black", is not purely a description of a physical attribute but an expression of a cultural identity. British Sign Language, with its own complex vocabulary, regional dialects and syntax, is one aspect of this culture. And deaf people aren't lonely, lifeless individuals who lie awake at night lamenting the tragedy that they can't hear the birds sing. In fact, Lichy laughs, "deafies" (a term many of the signing deaf community have reclaimed to describe themselves) "are the deepest sleepers around". No cockerel crowing, drunken shouting or Audi alarm will keep deaf people from their slumber.

"Most people's impression of deaf people is that they have no life and are missing out on lots of things," says Garfield. It's partly a result of how it is presented: "When people have written about deafness in plays, films and the media, they always say we 'suffer' from deafness, or we live in a 'silent' world. But our world isn't silent. That's rubbish. We're the noisiest people on earth!"

In Lichy's view, deafness is not about loss, it's about gain. "If only people knew about the deaf community, our rich culture and history, our parties and the closeness and pride that we feel in our shared identity. Our language is so colourful, so alive. That's our sound, that's our music."

There are more than 300 deaf social clubs across the country and three universities (Bristol, Wolverhampton and Central Lancashire) that have academic centres for Deaf Studies and BSL. A specialist mail-order bookshop (Forest Books) stocks more than 1,000 titles about sign language, deaf issues, history and culture. There are two terrestrial TV magazine shows, See Hear (BBC2) and Vee TV (Channel4), both presented in BSL by deaf presenters, and a deaf drama, Switch (which Garfield stars in) which has just finished its fourth series on BBC2. Deaf DJ and club promoter Troy Lee organises regular deaf raves that fill huge venues with thousands of deaf partygoers from all over the world. And an exhibition of deaf art (Deaf Wish) is on show this week at London's Woburn Gallery.

And that's just in Britain. In the US, you will find a national deaf beauty pageant (Miss Deaf America), a deaf university (Gallaudet, Washington) where all lectures are conducted in sign language, and even a deaf pornography company, producing films with deaf actors and the usual stifled dialogue, moans and groans, in American Sign Language. And every four years more than 4,000 deaf athletes from 75 countries compete in the world Deaflympics, now more than 80 years old.

This is just a sliver of the deaf world that has led Garfield and Lichy to view their daughter's deafness not as something that needs to be fixed, but as a passport to inclusion in a rich and varied culture. Perhaps, then, it is not so surprising that they have taken the controversial step of refusing hearing aids for Molly, who is now 14 months old.

"We both grew up forced to wear hearing aids. It's pretty awful to have this piece of equipment stuck to your ear from the moment you wake up to last thing at night," says Lichy, who, like many deaf people, discarded his own hearing aids once he reached adulthood. "The first day I stopped wearing my hearing aids I found it quite stressful, as I relied on them so much. But by the fifth day, I noticed my memory and concentration were starting to improve, and I felt more connected to myself and peaceful inside. I began to see more colour, light and harmony in my vision. Everything became more alive and vivid."

"Many people have the perception that if you are deaf you can just put a hearing aid in and you will hear," says Garfield. "But it's not like that. For some people with a mild hearing loss, a hearing aid can help. But you can't cure profound deafness with a hearing aid. It's like blind people; you can't just put on glasses and see again."

The couple's stance has been questioned by medical professionals. "When we said that we didn't want a hearing aid for Molly the doctors reacted very badly," says Garfield. "They really changed their attitude towards us. Before, they were happy with us and our parenting skills. They had written to us to say that Molly was 'in an optimal home environment'. But then they decided we were bad parents because, in their view, we were denying her an opportunity to develop. We have received several letters asking us to reconsider."

For Garfield and Lichy, this is all about accepting Molly as she is, rather than trying to remould her into the hearing child she isn't. "It's an important time for Molly to learn about her body in its natural state," says Lichy. "How to use her hands and her vision. To give her hundreds of decibels straight into her ear with an amplifying device, when she can't control the volume herself or say if it's painful, is just wrong. A typical hearing aid for her age and level of deafness amplifies to 120dB or more. That's like standing next to a car horn, or a jackhammer banging away next to you. How can she learn to play, to focus, to concentrate with noises like that blasting into her ear? We refuse to do it to our baby. If she wants to wear them when she is older, then that will be her decision, and we won't stand in her way."

The couple are also adamant that while they are proud to be deaf and bring Molly up as part of the deaf community, they are not "anti-hearing". "Hearing people are also part of our world, they are our friends and our family," says Garfield. "We meet them every day when shopping and so on, so we want Molly to learn speech and be part of the hearing world too. We have already found several speech therapists with fluent signing skills to help Molly develop her spoken language."

They say Molly is on a developmental par with her hearing contemporaries, with a wide vocabulary in both sign language and English. "We are giving her English too," says Garfield. "She is copying my lip patterns. She is already signing around 50 words and can understand three-word sentences, which is as much as hearing children her age and a much larger vocabulary than profoundly deaf children of her age with hearing aids or cochlear implants and no access to sign language."

Still, they continue to feel under pressure to explain and defend their actions, and to fight against the assumption that what they have chosen for their child is wrong. Both have long experience of living with deafness, says Garfield. "We have deaf friends and families. But these doctors, and many other people, generally know so little about the deaf community, culture and language, yet they assume they know what is right for us. They have a perception that deafness is a physical failing that needs to be corrected. For us, it's just a different and equally valid way of being"