When attorney Michael Chatoff argues his case before the Supreme Court today, he will not be listening to the probing questions of the justices. He will be watching a television screen instead.

Chatoff will be the first deaf attorney to argue before the nation's highest court, and to help him out, the justices for the first time have allowed in their hallowed hall electronic communication equipment designed by a Rockville firm to translate the spoken word into writing.

The system, which is also scheduled for use in an Illinois case today, could persuade usually conservative judges to accept technology where tradition has reigned.

As the justices ask Chatoff questions, a court reporter will take down the queries, which will be transferred to a computer outside the courtroom. Within three seconds, the computer will translate the court reporter's phonetic shorthand into standard words, which show up on a television-like computer screen in front of the attorney. The computer can distinguish between shorthand for phonetically similar words such as there and their, based on the context of the phrase.

Chatoff, 35, who became deaf several years ago while in law school, then can answer the questions verbally. Part of the system will be placed outside of the courtroom because it has a noisy fan, said Don Grigg, a spokesman for the company. Chatoff will be using the system without charge, Grigg said.

"We have merged the microcomputer technology with the professional skill of the shorthand reporter," said Donald Nixon, president of Rockville-based Translation Systems Inc.

According to a court spokeswoman, today will mark the first time the justices have allowed electronic communications equipment in the courtroom while court is in session. Cameras and tape recorders still are banned. In January Chatoff asked the court if he could use the computer system, and the court gave its approval without comment.

In other cases, Chatoff has relied on manual note-taking, which has furnished him with only 50 to 55 percent of what was said, Grigg said. The case today involves a 10-year-old deaf girl who claims the Education of the Handicapped Act requires that the Hendrick Hudson School District in Westchester County, N. Y., should provide her with a sign-language interpreter in her classroom.