This ability, that ability - who cares as long as it works?

The deaf and the hearing mix in life, so why not on the stage? Brian Logan on a radical new play about sex and the senses

The sign language interpreter, gesticulating downstage right, can be a bit of a distraction when you're watching a play. Maybe it's because we can't stop looking at those dancing hands. Maybe it's because the reactions to the play of its deaf spectators, and of those who can hear, are slightly out of sync.

Theatre director Jenny Sealey, who is deaf, has no truck with "the sign-language interpreter in the corner of the stage, far away from the main action. It really pisses me off." The company she runs, Graeae, have been working to embed sign language and audio description in their theatre work, not as a for-one-night-only bonus, but as integral from the get-go. On Blindness, which opens this week at London's Soho Theatre, will be our chance to see, or hear, whether the experiment is paying off.

The play is by newcomer Glyn Cannon, and is co-produced by three of the UK's brightest companies: Graeae, who've been Britain's flagship company of disabled theatre practitioners for over 20 years; the physical theatre group Frantic Assembly; and the new writing specialists Paines Plough. In what looks like an act of esprit de corps gone mad, it has no fewer than four directors: Sealey, Paines Plough's Vicky Featherstone, and Frantic's Scott Graham and Steven Hoggett. Its cast includes non-disabled and disabled actors. Which is just the way Mat Fraser, one of those actors and the presenter of Channel 4's Freak Out, likes it. "The disability politics part of me doesn't think there should be all-disabled plays or all non-disabled plays. We are the world: we should mix up onstage as well as on the street."

Cannon's play is not, contrary to the title, exclusively about blindness. "It's not," says Sealey, "Children of a Lesser God for blind people." She's referring to Randa Haines's award-winning film, the 1987 deafness-themed tearjerker. "I'm not," she says, wrinkling her nose, "a fan." Graeae isn't interested in jerking anyone's tears for disability. "I watched Notting Hill the other night," says Sealey, "and there's a wheelchair-user in it who talks about how tragic her life is. Now, is that all that anybody can write about the disabled?"

On Blindness is something else entirely. "It's about relationships, it's about sex," says Sealey. "It's about what happens on a Friday evening to two different couples. It features a woman who has ideas, opinions, she's sexually active. And the fact that she's blind is a part of who she is, but not the only part." Indeed, it looks as if the sexual content of Cannon's play may make more waves than its treatment of disability. Mat Fraser talks excitedly about circumventing the laws prohibiting onstage erections. And about the scenes featuring masturbation and (partial) nudity. "A nude man onstage has a different impact to a nude woman," says Fraser. "And a nude disabled person has far more of an impact, doesn't it? And so it goes on, up in levels. And we've got it all."

But what excites Sealey is that the production is pioneering an inclusive new stage language. "Is there a better way to access deaf audiences," she wants to know, "than making them watch the interpreter in the corner?" Audio-description for blind people isn't much better. "To take Rita, Sue and Bob Too as a random example: you've got all these working-class Yorkshire accents onstage, but the audio-describer will still be speaking RP English into people's headphones. It's a separate entity from what's happening onstage. We want to make everything absolutely integral."

The three companies have set about this firstly by learning to communicate among themselves in the rehearsal room. (One performer, Karina Jones, is blind. Another, David Sands, is deaf.) The actors have all acquired rudimentary BSL skills, and the script pre-empts the need for audio-description. Says Sealey: "It's about making sure that the dialogue contains the necessary visual information." The example she cites is that a line like "Have that back" would become "Have this watch back." Design (by Improbable Theatre stalwart Julian Crouch) and music (by Nick Powell of Suspect Culture) are also being created, in tandem, with access for hearing and visually impaired people very much in mind. Sealey hopes that a dramatic language will emerge that satisfies all viewers' requirements equally.

Against the charge that a too-descriptive playtext might alienate sighted punters, Sealey points out the advantages of description: it can trigger the imagination to look beyond what the eyes see. "A good exercise would be for everyone to take a piece of artwork, and describe it to a friend. Then see the difference between what you've described and the image in your friend's head." Likewise, a knowledge of sign language brings fresh insights into physical communication. "One BSL sign, accompanied by many different facial expressions, can mean many different words," explains Sealey. "To have that information makes an actor acutely aware of what he or she does physically."

Underpinning all this is Sealey's belief that audience members each receive information in different ways, and may be surprised by how much they can receive in seemingly "foreign" languages. She believes that theatre as a whole would be richer, and more inclusive of disabled audiences, if only its practitioners "would keep ideas of accessibility in their heads. It's not rocket science. It's just taking a little time to think."

'On Blindness': Soho, London W1 (020 7478 0100), Thursday to 13 March