"Hello, this is Helen Hayes . . ." A microphone the size of a small grapefruit nearly obscures her features, but there's no mistaking the celebrated voice, which crackles now a bit like breakfast cereal. In a mousey-beige studio above the din of Broadway and 42nd Street, Helen Hayes is in the midst of a taping session for "The Best Years" -- her daily two-minute radio commentary, beamed to the nation's elderly.

The First Lady of American Theater officially retired 11 years ago, but the stage was apparently all she retired from. She's since had a TV series, "The Snoop Sisters," with her good friend Mildred Natwick. She's made two films for Disney ("Dinosaur" and "Candleshoe") and a TV movie with Fred Astaire ("A Family Upside Down"). Recently, she popped up on an episode of "Love, Sydney."

A year ago, having reached the age of 81 with no noticeable ill effects, Hayes stepped into Lowell Thomas' shoes as a spokesperson for senior citizens, dispensing public service advice, good cheer, and homey reminiscences over 175 stations in the country. (In Washington, WEAM 1390-AM carries the program weekday afternoons at 2:40.) More than 7 million Americans over 65 are living alone. Eighty percent of those are women with what is politely termed "disposable income." They make up a growing and lucrative market and the insurance barons of Mutual of Omaha, who sponsor "The Best Years," pay Hayes "very well" to address them on such matters as housing, medical bills, loneliness and, yes, even sex.

Twice a month, Hayes trips into the city from her home overlooking the Hudson in Nyack, N.Y., to tape a cluster of commentaries, then usually dines out afterwards and catches a play before heading back. At this particular taping session, she's chatted about the letter carrier who used to make his way up her driveway and who once counseled her to sprinkle borax around her apple trees. She's preached the virtues of self-reliance ("There comes a time when you really have to say, 'Get up, old girl' or you run the risk of making the bed your habitat.") And she's lauded Phyllis Diller, who, being 65, apparently falls within Hayes' bailiwick. ("I'll trade some of my classic good taste for her colossal comic humor.")

Now, her voice all warm and jaunty, she's waxing about Sid Caesar and the early days of television. " 'Your Show of Shows!' Live television! That's all it took to get you hooked for life. Until 1958, Sid Caesar was considered one of the funniest entertainers. He earned a million dollars a year then, but couldn't find a place that sold happiness . . . Oh dear! . . . um, err . . . But couldn't find a place that sold happiness . . ." Like a Victrola runing down, the chipper tone is fading. "As happens so often, the pressures of success overwhelmed him. Drugs and alcohol became the slow, but sure, avenue to disaster. His health deteriorated . . . His health deteriorated? My heavens!"

Rattled, Hayes puts down the script. "Do you know I never knew that! I never had any idea. Drugs and alcohol? Oh my gosh. Is this true?"

Assured it is, she replies, "Well, I lead a sheltered life sometimes in my Nyack hideaway. I read that piece in the Times the other day about the cocaine epidemic in the movie community. Having been there, I don't think it's that those people are maladjusted and don't know how to use all the money they get. I think it's that work in films is difficult--the long hours, the boredom, all that waiting around until you go on and then pushing yourself to be fresh. Especially if you're trying to be funny. Well, I certainly don't think it's a fault in Sid Caesar's character. It's the job he was doing."

Hayes readjusts her glasses and attacks the script with renewed zeal, building to the upbeat ending. "I do hope Sid Caesar will come back to entertain us with real humor, because I agree with him when he said, 'Throwing a pie isn't funny. Not throwing it is.' "

"Take two," calls out the engineer in the recording booth.

"Hello, this is Helen Hayes . . ."

This time, the reading is perfect -- compassionate and concerned. You'd swear Helen Hayes had known Sid Caesar all his troubled life.

"Radio! I do love it. Being a spokesman for my generation. Isn't it fun," Hayes says, after she's disposed of the afternoon's work -- 10 scripts in all -- and trotted around the corner to Sardi's, where she's now sitting ramrod straight before a cup of black coffee. "Oh boy, I think we have to be told an awful lot -- to never give up, to keep in there. Three or four of every 10 scripts are concerned with diet and exercise. Exercise, exercise, exercise. Sometimes you say to yourself, 'I've been working so long, serving the world to the best of my abilities for so many years. Let me off now!' We old folks need to be constantly goaded. It's what I said in one of those scripts today. 'Get up, old girl!' "

Hayes is wearing a neatly tailored suit with a striped silk scarf tied in a perky bow. Her white hair is neatly piled on her head. The eyes, crinkled as if with Christmas merriment, are quick and clear. Central Casting would probably crossfile her under Quintessential Grandmothers or Mischievous Octogenarians. But they could also put her under Sharp Cookies.

"Last night, I ate a piece of hard candy," she is confessing, "and I broke something in my mouth. My tongue is still all swollen. I don't know how I got through those scripts today. Anyway, I lay awake in pain all night. And I thought, 'Here you are 82 and acting like a damn fool eating that candy!' Then I got very depressed. I'd been pushing a lot. Two weeks ago I had to go to bed with sciatica. Doctor's orders. And breaking a tooth on top of that! Well, I got to thinking that maybe 82 is the last stand. What is that line of Hamlet's? 'Do not wait upon the order of your going.' Maybe, I thought, this is the time to go. Don't prolong your exit, Helen. Just go."

She emits a gentle, ladylike sigh.

"But when I got to the dentist this morning, I learned that all I had really broken was a cap on the tooth. Well, that's not so bad. And walking to the dentist, I picked up these lovely leaves along the way. And then I got thinking of the work to be done in the rose garden -- getting the colors straightened out. Somehow they got all mixed up! And of course, I knew I had these radio programs. The old fire horse began responding to the bell. I guess I just have to be meeting a deadline, an obligation. When you've spent 75 of your 82 years getting to a theater on time, maybe you can't stop it. The habit is very strong to want to connect, to communicate."

With a triumphant Broadway career behind her, a stack of honorary degrees, an independent income (she uses her radio salary to endow scholarships in acting and playwriting), homes in Nyack and Cuernavaca, Mexico (both with heated pools), a live-in companion, not to mention the general adoration of the nation, it might be argued that Helen Hayes is passing out advice on aging from a decidedly privileged position.

She reflects a moment. "Oh, I suppose some of my listeners must say, 'Get her! Listen to her talk! What does she have to complain about?' When you seem to have everything you could wish for, it makes you a bit self-conscious about admonishing people to take an upbeat view of their lives. But, of course, nobody has it all. I would like to have had a large family. I achieved one daughter, Mary, but I lost her. And because I was crazy at not having more children, we adopted a son the actor James MacArthur . A wonderful fella. He's a great comfort to me.

"But every life has its ups and downs. I remember when my husband, Charlie MacArthur died. I thought, 'Now Charlie's gone and I've lost Mary. Jim has gone off and is married and I'm alone. I have a choice. Will I be happy or unhappy for the rest of my life?' Simple as that. And I chose not to accept defeat. That's the one bit of wisdom I've learned. To choose the positive if you can. As you get older, you're apt to be impatient and critical with people. That's what I'm working on now -- not being critical. I guess because I've been a performer all my life, I can stand off and look at myself and say, 'Now, wait a minute, Helen, that's not a good way to play that scene.' You just have to keep trying to correct all those false moves you make."

Perhaps because everyone else sings her praises, Hayes also has developed a beguiling modesty about a stage career that began in 1905 with her appearance in "The Royal Family" and ended in 1971 with "Long Day's Journey Into Night," when an acute allergy to backstage dust forced her out of the theater. In between, there were some 70 roles in such plays as "What Every Woman Knows," "Coquette," "Victoria Regina," "Twelfth Night," "The Skin of Our Teeth," and "Harvey." Not too long ago, she turned down an offer to appear in a television movie for CBS, which would have taken her to Hollywood, because she didn't relish the prospect of "looking like a sack of meal" on the screen and "damned if I was going to diet." Besides, she wasn't sure they really wanted her. Hollywood brings out all her professional insecurities. On a set, she confesses, her courage "leaks out at the seams."

But she won an Academy Award!

"Two," she notes, discreetly. "I don't know what it is. I always feel like a second-class citizen out there."

But she's Helen Hayes, for Pete's sake. Revered!

"Oh, I'm revered now as an icon. I long ago gave up any daydreams of being revered as a great actress. None of that was possible for me. I don't think I ever felt important enough. And in show business, you have to feel important to make others think you're important. No, I was a professional much too early in life to have the chance to yearn, to palpitate, to say, 'I'll do it. I'll make it some day.' It was a job, a fascinating and delicious job. But a job.

"I loved all those years I was touring -- Detroit, Cleveland, Milwaukee -- on the old Theatre Guild route. But I got tired of it after a while and I took to living in the zoos. Yes, I went to the zoos all the time, because I knew I wouldn't get a single question from the animals about how I made up my face for the last act of 'Victoria Regina.' I didn't have to explain to them that I didn't have apples in my cheeks or answer a whole lot of foolish questions. Oh, the zoos saved my life.

"Now I'm treated extraordinarily affectionately. I say extraordinarily, because sometimes I can't believe all these people getting so emotional over me. But they do. I've become an icon and I have to face it. I smile and say thank you and how lovely to hear that. But sometimes, I think, 'Dammit, I sure could have used some of this adulation when I was working and getting paid for it.' Oh, I was always happy in the theater. No, I wasn't. I was miserable most of the time. But it would be a towering ingratitude to say that I'd have done anything else with my life."

Her eyes twinkle.

"So I won't."