The name of Tom Lehrer is still a password that instantly admits the speaker to a select circle of survivors of the 1950s and early '60s. Lehrer, more than any other black humorist, even Mort Sahl, crystalized the scornful bemusement felt by a whole generation.

His songs were definitely judgements on the times, for instance, "The Old Dope Peddler," or "Masochism Tango," or "Vitican Rag." The songs, celebrating necrophilia, Oedipal urges and murderous impulses, were tonics for bland times.

In those days Lehrer was a figure of mystery and speculation. There were rumors that he was a graduate student in mathematics at Harvard (correct), that he sang his parodies and sardonic ditties in Cambridge coffee houses (also correct), that he had committed suicide in 1960 (incorrect). His hard-to-find record album was passed from hand to hand, a treasured anti-establishment talisman.

And some things haven't changed. Finding Tom Lehrer to discover whether he had burned out or whether the reality of the times killed his ability to form satire, was difficult. After a long delay, a form letter from a Cambridge post office box listed on the back of those now-tattered record albums said Lehrer wasn't writing anymore but, yes, the albums were still available.

Occasionally viewers of public television's "Electric Company" can detect his Harvard-accented, bouncing voice. But it isn't his parody about "College Days" with the unforgettable line "soon we'll be sliding down, the razor blade of life..." On kiddle television the songs are about "silent e" and the "plural s." A spokesman for the show confirmed it was the former musical parodist who wrote and sang about a half-dozen ditties for the how-to-read show before it went out of production two years ago. The last address the spokesman had was the University of California's Crown College at Santa Cruz.

Sure enough, after one phone call, Tom Lehrer is on the line. He has just turned 50, he says. No, he no longer performs and he hasn't written anything since a couple of Polaroid jingles, and that was some time ago. "My head just isn't there, anymore, but if somebody calls with some money - "

Over the phone there is very little reminiscing about the times he helped to satirize. In song after song, heard on concert tours in major cities and college campuses, he pounded the cliches into dust. Idolized, Lehrer played London's Royal Festival Hall, New York's Blus Sngel and San Francisco's Hungry i, where he attracted the largest audiences since the Limelighters in 1959.

His indelible turning point came one evening in 1967 when he performed his "Vatican Rag" on New York's Channel 13. Written just after Vatican II, the song offered Lehrer's preview of a new jazzed-up Catholic liturgy - Ave Maria, gee it's good to see ya, doin' the Vatican rag...").

A switchboard at Channel 13 about but burned up that night. By next morning the station had logged more than 400 protests. Catholics, southerners, westerners, Dr. Werhner von Braun, the entire military-industrial complex (before most of us knew we had a military-industrial complex), each got raked over the keys of the Lehrer piano. Then that piano fell strangely silent.

Yet, today, Lehrer still gets royalties from his records, a few dollars now and then. He teaches two courses at Santa Cruz, one in math for the social sciences and one on American musical comedy as literature. That one he particularly enjoys, saying, "I don't get people in that who have to take it."

Six months a year he lives in Santa Cruz. The rest of the time he spends at Cambridge, where he earned a masters degree in mathematics (statistics and probability) but never did go on to get a doctorate. Of Cambridge, he says, "They use their brains there.Out here it's a vestigial appendage."

"About once a week when I'm at Cambridge somebody tracks me down. Usually it's some kid ripping off the phone company with a black box. Or a reporter who's doing a 'whatever became of -' kind of thing. I'm torn between being rude and flattered. But I discourage interviews because I have nothing to plug."