Twice a week Marie Larson, who has been blind since she was 3 years old, places a book on the top of a machine near her office, throws a switch, and takes a seat to "read" for two hours.

Then, deliberately and in a stilted, almost robot-like voice, the machine reads aloud. If there is a passage that is particulary complicated or hard to understand Larson can throw a switch and the machine will repeat it. If the machine says a word she doesn't recognize, she can throw yet another switch and the machine will spell it for her.

She is using a device called the Kurzwell Reading Machine, a new and experimental product that has the potential for dramatically changing the nature of the rehabilitation, education and training of blind people.

"We think it's the greatest development since Braille," says Michael Hingson, a blind person and chairman of the National Federation of the Blind's committee on research and evaluation.

"The reading machine will make a lot of material available to blind people that just hasn't been available before."

"It's probably one of the biggest breakthroughs in blind educational aids we've ever had," said James Johnson, marketing director for the U.S. Office of Education's Bureau of Education for the Handicapped.

In the last year, 30 of the machines have been placed in schools, libraries and departments of education around the country by both the Bureau of Education for the Handicapped and the federation of the blind.

There, they are subjected to an ongoing process of criticism and evaluation by blind users. Those reports are sent on to Combridge, Mass., where the machines are designed and undergo continuous modification.

Initially, for example, each machine cost $50,000 to produce and weighed 150 pounds. By next month a desk top model will be available for less than $20,000.

It will be about the size of two large attache cases and will be easy to carry, its designers say. Within three years, they hope to have the cost down to less than $5,000 and eventually, they say they want to make the machine available to every blind person who needs one.

Invented by Raymond Kurzweil, a 29-year-old graduate of MIT, the machine can read most common styles of type at a speed of about 150 words a minute - the normal rate of speech.

When a user places a book, memorandum, letter or pamphlet face down on the machine and throws the "read" switch, a specially designed system scans the page and transmits electronic images to a computer.

The computer is programmed to recognize letters on the page, group the letters into words and then compute the pronunciation of each word.

To enable the machine to pronounce words properly, the computer's memory has has been fed more than 1,000 linguistic rules, plus 2,000 exceptions to those rules. The actual speaking is done with a speech synthesizer.

"The voice is a little bit tough to get used to, but we find that with an hour or two of practice, you can understand it easily," said the federation of the blind's Hingson.

"It's like getting used to a foreign accent," said Dorothy Harris, 48, who's been blind for the past 13 years.

Two or three times a week, Harris spends an hour with the reading machine at Blind Industries and Services. She's had "The Bermuda Triangle" read to her and she's about halfway through a book of reflections by a Baltimore area disc jockey.

"It does what any (human) reader would do for you," said Harris.

One of the machine's real benefits, say blind people and people who work with them, is that it gives the blind access to a wealth of written material that is not available in Braille or on tape recordings.

"A lot of blind students who previously had to hire people to read to them or rely on volunteers will now be able to do it themselves," said Marilyn Mortensen, special services supervisor for the Virginia Beach public library.

Virginia Beach has had one of the reading machines for about a month. "It's marvelous. It has tremendous potential and it's going to be of real assistance to the entire blind community," said Mortensen.

A number of blind business people, including a few blind lawyers, have asked to use the machine this summer to read such material as business letters. memorandums and other material, Mortensen said.

With the start of the school year in September, special education teachers from Virginia Beach and the surrounding vicinity - Norfolk, Portsmouth, Chesapeake - will use the machine regularly with blind children.

In Baltimore, at the Maryland School for the Blind, teacher Patricia Riley has been using the machine with her students for about two months.

"The children love it and they are able to learn very quickly how to operate it," said Riley. "They machine is self-motivating as far as teaching goes. Children will come in on their lunch hour to make up a session if they miss a class."

Leaders of the blind community, while enthusiastic about the potential of the reading machine, do have some real concerns, however.

The Kurzweil machine is one of the few examples of how technology has been helpful to blind people," says Ralph W. Sanders, president of the National Federation of the Blind.

"But it won't be helpful if educators begin to think that now they don't need to teach Braille. If a child doesn't learn Braille, he loses an important communications skill."

"It will never replace Braille," says the federation's Hingson. "Braille will always be my primary means of reading and writing."

But Hingson has used the machine to have Jules Verne's "The Mysterious Island" read to him. I'm somewhat of a science fiction nut and that book was never translated into Braille," Hingson said.

Similarly, he tried once to get a tape recording of Arthur Schlesinger's "The Imperial Presidency" from the library and found there was a two-year waiting list. The book had not yet been put into Braille, so Hingson had the machine read it to him.

At Blind Industries and Services, use of the machine is shared among several people and more and taught to operate the machine every month.

On Monday and Wednesday afternoons when Marie Larson, 25, has her turn at the machine, she concentrates purely on reading for pleasure.

"I like working the machine a lot more than I used to," said Larson. "I enjoy it a lot and I know it's going to give blind people a much wider range of reading material."