Washington — There was a moment of such complete silence that you could have heard the click of a Leica in the media logjam of the redecorated White House press room. Then a voice announced, in the style usually reserved for the President, ''Ladies and gentlemen, the press secretary of the President of the United States, Mr. Jim Brady.''
In rolled Mr. Brady, still confined to a wheelchair following the assassination attempt on the President's life which had wounded him and kept him away from his job for the last several months. His visit was a poignant moment in a room where tough professionalism usually reigns. There were cheers and applause for the man ''whose courage has been an inspiration to all of us,'' as President Reagan said in his remarks.
Both the President and Mrs. Reagan were present to welcome back ''the Bear,'' as he is affectionately known, and to cut the red, white, and blue ribbons on the shiny new press room. Brady, although visibly moved, bantered with the reporters in his old style, cracking ''I miss most of you.''
Some of the reporters, like Richard Jaroslovsky of the Wall Street Journal, were sporting tiny stuffed teddy bears on their lapels with the slogan, ''This one's on the Bear.'' Said Mr. Jaroslovsky: ''It's not the surroundings, it's what goes on in this room'' that counts.
The old press room, furnished in a dun brown, had reached a stage of such disarray that it had begun to look like a journalistic zoo. The new room, as Los Angeles Times bureau chief Jack Nelson suggests, ''looks a little like a chapel, but that's all right.'' Gone are the battered furniture and folding chairs, the wads of old papers, the splotched rug.
In what most journalists agreed in a random survey is a distinct improvement, the place has been redone in lighter, brighter off-white and royal blue. Shiny white, ribbed wallpaper covers the walls of what was once the former White House swimming pool. The old decor has been replaced by fixed white theater seats covered in royal blue polyester tweed, a blue rug, and a bright blue velvet podium curtain to replace the dusty old one.
Helen Thomas of UPI, who has a front-row seat, says that although the room is still too small, she likes the way it looks, adding, ''We're used to chaos and it will become that.'' Ted Knap of Scripps-Howard thinks movable seats would be better, and Anne Garrels of ABC says she misses the ''coziness'' of the old arrangement - the living room ambience of sometimes sitting on the floor - but likes the new brightness. Sue Mathis of the White House Office of Media Relations, wearing a ''The Bear Will be Back'' button, says, ''It's a cheerier atmosphere. It used to look like a dungeon.''