Virtual reality can let video game players escape from the real world but a group of researchers are using virtual reality to help the blind join the real world more, by navigating real places.

Researchers at the University of Chile and Harvard Medical School are using three audio-based PC games that allow players to navigate a labyrinth, a subway system and real-world buildings based on audio cues. Essentially the games work by interpreting information generated by spectral sounds like footsteps and door knocks, said Lotfi B. Merabet, PhD of Beth Israel Deaconess Medical Center and Harvard Medical School and co-author of AER Journal: Research and Practice in Visual Impairment and Blindness.

The player uses a keyboard to move and interact with the virtual world. By sequentially interacting within the virtual 3-D environment, the user learns to build a spatial cognitive map of their surroundings.

The goal was to develop audio-based gaming to help blind children develop spatial, cognitive and social skills.

(We've) concentrated on developing the gaming software as a rehabilitation tool to allow blind users to survey unfamiliar buildings before actually navigating through them in real life, as well as conducting brain imaging studies to uncover how the brain of a blind individual accomplishes this task, said Merabet.

According to the World Health Organization, there are about 314 million visually impaired people worldwide and about 45 million of them are blind.

There are over 50 audio-based games for the blind currently available, according to Kelly Sapergia, who reviews games created by and for blind people for the American Council of the Blind's Main Menu radio program.

She said these vary from pinball to Space Invaders-style games to GMA Tank Commander, which is a World War II game that lets you drive a tank and shoot various weapons at enemies.

Blind gamers also have access to the classic text-based games that preceded the video game explosion, including titles like Zork from Infocom. Sapergia said blind gamers can plug in an audio synthesizer and have the text-based adventure read to them.

There are even games that offer a level playing field regardless of sight. Since 2001, AllinPlay has offered subscription-based online community games like Texas Hold-em, Crazy Eights, and The Anagram Game that were designed for both blind and sighted people.

Previous research efforts have also become games for the blind. In 2005, the Utrecht School of the Arts in the Netherlands developer a racing game called Drive in cooperation with the Bartimus Institute for the Blind. The game lets players drive a shuttle along a fixed track with a co-pilot named Bob. But compared to the millions of copies of PC and console games sold every week, the market for games for the blind is tiny.

There's a community of blind gamers, but I think the main drawback has been that the big game publishers like Nintendo and Sony haven't created games that are more accessible for blind people, said Sapergia.

Merabet and fellow researcher Jaime Sanchez from the Department of Computer Science at the University of Chile do not view audio-based computer games as a replacement for current rehabilitative techniques but they hope this research will provide a complementary technique.

(Editing by Belinda Goldsmith)