It's just an unassuming radio show that costs about $700 a week to put on. But in the taping of "First Hearing" in a Manhattan studio, it has become the runaway hit of classical music radio.

For the music lover, "First Hearing" combines the challenge of "Information Please" and the stimulation of a slightly contentious scholarly forum. The formula is simple enough: Three expert listeners sit around a rectangular table in a musty radio studio hearing three or four recordings, and then a moderator calls upon them in turn for their impressions-yea or nay.

Once broadcast exclusively to New Yorkers, "First Hearing" is now distributed by Parkway Productions of Bethesda to 80 "good music" stations around the world, making it the most widely heard classical music program. You can hear it weekly in Anchorage, Key West, Homolulu and points beyond. In Washington, station WGMS has given "First Hearing" are new releases, and that alone appeals to legions of radiophiles.

But the program adds the lure of the guessing game. Both the experts and the listening audience are kept in the dark about the conductor or players until they have rendered their critical judgments. Usually, only the composer and the name of the work are revealed beforehand.For panel member and listener, this heightens the challenge and makes the results more unpredictable. Music addicts sometimes get so hooked on what the car radio is emitting that they find themselves waiting in the garage to hear what composition it is-and the wait gets longer with "First Hearing," because you also wait to hear what the panel says. "I almost missed the opening of a Kennedy Center concert recently because of that," confesses a Washington music critic.

A listener may disagree with the critics-and more often than not they disagree with each other. "No one has ever come to blows," says producer George Jellinek of station WQXR, where "First Hearing" is taped every Wednesday at 9:30 a.m. "Furthermore, hard feelings over disagreements are rare." Sometimes the tones of voice get a little testy. But that, like the program itself, is understated.

The panels vary in makeup from week to week, but by now millions have become familiar with the voices and views of its founding fathers, critics Irving Kolodin, Martin Bookspan, Edward Downes (also the Metropolitan Opera Quiz moderator for 21 years) and moderator Lloyd Moss. Moss, by the way, is known elsewhere as a narrator of TV programs and of ads for products like Listerine. The show has also made familiar to those same millions its previously obscure theme music, Swedish-American composer Ingolf Dahlhs intermezzo from his "Music for Brass Instruments."

Jellinek put "First Hearing" together during his first year at WQXR. At first Kolodin, Downes and Bookspan were the regular panelists-always, that is, except when the genially absent-minded Downes would forget to come. Then Jellinek would step in as a substitute. "Kolodin was a natural, because of his enormous reputation," say Jellinek. "Downes came in because he was famous from the Met broadcasts. And Martie came in because he was familiar to WQXR audiences as my predecessor as the stationhs music director.

"As the years passed it was necessary to form a considerable cadre of persons on whom we could draw. As of now Downes and Bookspan normally alternate each week, and Kolodin is on an average of once a month. We are trying to have more performers on the panel, to vary the points of view. Sometimes, though, this is a problem because newcomers sometimes are not accustomed to the discipline of radio and will become somewhat discursive." So far the performers have included Itzhak Perlman, Andre Watts, Alexander Schneider and Julius Rudel.

Jellinek organizes his programs around common elements. "Maybe a program will be organized around a single composer, or the piano, or the violin. Though sometimes in the dog days of the summer I have to resort to a hodgepodge."

On a recent Wednesday, Downes, Bookspan and Opera News editor Robert Jacobson were the listeners, and they failed to reach a consensus-either yes or no-on any of the three performances. They did agree, however, that all three works programmed were "masterpieces."

The initial record took the hardest beating. It was Zubin Mehta conducting the Israel Philharmonic in the opening movement of Mozart's 40th Symphony. It drew one yest and two emphatic no's.

The vote was the same on pianist Maurizio Pollini's interpretation of Beethoven's "Hammerklavier" Sonata, but the no's were more muted.

It was merely a matter of degree, but bernard Haitinck's performance of Strauss' "Don Quixote" came out best. There was one strong yes, and the others were at least lukewarm.

Oddly enough, each of the favorable votes was cast by a different critic. None had heard any of the interpretations before. Sometimes their differences are over fine points of the performance and other times about the overall interpretation. Occasionally a composition itself will come under attack.

"First hearing" demonstrates that the musical taste of the listener can be as subjective as the character of the in- terpretation. Chatting after the taping session, it became apparent that for all the differences of opinion, the critics' general philosophies of what to listen for were relatively close. But what each heard that day affected each of them differently.

On Zubin Mehta's Mozart with the Israel Philharmonic, it was Bookspan who struck his nect out in its favor and it was this opinion that drew the sharpest dissent of the hour. Bookspan maintained that "the whole performance had (special) care and attention to detail, along with a febrile intensity that I thought was fine without becoming overwroght."

Jacobson first condemned it by faint praise: "It was a very intelligent and sensitive blueprint of the music." Then he complained about "a missing sense of urgency. There was a glossy and elegant fabric and nothing else for me. I kept thinking we've heard the music, now let's hear the music."

Downes was even harder on the performance. "That sense of urgency amounts, I think, to a sense of tragedy. Mozart wrote only 2 minor key symphonies in his life, and this particular key is associated with utter despair and that simply was not present at all."

Asked later what interpretive leanings he amy have, Bookspan said, "Mine is a general one which discounts the importance of perfection in the execution in favor of personalizing the score in a way that there's no mistaking the fact that there's a human mechanism at work there responding to those abstract notes on paper. I'd much rather have the highly personalized perversity that we've all alluded to in talking about Von Karajan, the perversity of self-aggrandizement and narcissism, which sometimes he makes you brutally aware of . . . "

Downes was the critic who found Pollinihs Beethoven "immensely" compelling, while granting that the work is of such notoriously herculean proportions and technical difficulty that it is "superhuman" and no pianist would be capable of an "ideal" performance. But Downes found the interpretation to be "marvelously suggestive" of an ideal, and pointed to "shifts of mood from the explosive quality of Beethoven in the heroic mood to sudden delicacy."

Jacobson agreed with Downes' description of the execution, but then proceeded t take the recording apart as one "I would not really want to live with." He complained, "I really felt there was not a great sense of the inner tension or a very big architectural grasp. And this is important because it is a very sprawling work."

Bookspan compared the performance to the Mozart he had liked. "I kept thinking, here is the absence of the two qualities that my colleagues found absent in the Mozart-a lack of tension and of drama." Bookspan's fpersonal preference is for a rarely performed orchestration made of the sonata by the late conductor Felix Weingartner-and he agrees that the work transcends the limits of the piano.

Asked what style of playing he leans toward, Downes replied, "I think the thing I look for and that gives me the biggest bang is when I feel that the performer has connected with the composer, and I feel that I know, in this case, exactly what Beethoven meant when he put those notes on paper. That moment comes through like an electric shock."

It was on the recording of Strauss' "Don Quixote" that there was the least disagreement (only the last 5 variations and the epilogue were played). Jacobson professed to being "tremendously moved" by Strauss' music, and thought that the conductor and the solo cellist" captured very much of the music's expressivity, drama and emotion."

Downes' reaction was one of "brilliant, but." What bothered him was the cello solo at the very end. "It is music that can very easily move me to tears," he said, "and on this occasion it was sentimentalized almost beyond bearing."

Bookspan's reaction was the reverse. He thought "it got better as it went along," but acknowledged that his misgivings might be more because of the sound than the performance.

Jellinek departed slightly from the others on the issue of precision. "I reeallize that everythink in life is a compromise," he said, "but I would put a higher price on technical perfection than some of my colleagues. Still, a fine performance must reach into the soul of a composer."

There was general agreement that perfection is marvelous, however, so long as it does not interfere with the composer's message. The heifetz interpretation of the rigorous Sibelius violin concerto was cited. "He begins his work at a level that most other violinists are fighting to attain," downes observed.

Interviewed later, that other mainstay of "First Hearing," Irving Kolodin, reflected the view of the others that superior musicmaking is not just a technical matter. "I am not a literalist in the sense that I wish to hear every detail of the score set forth in clairty . . . and I look for a degree of insight into the specific piece of music and an understanding of the composer's purpose."

Kolodin voiced a complaint that was also repeated by some of the other critics-that the present-day record industry is sometimes more concerned with quantity than with quality. "I think that the production of records in the long-playing period has been for the most part unwise and lacking in judgment," Kolodin said. "There was a time when a record was a proof of somebody's standing in the musical world. It doesn't mean a damn thing anymore." CAPTION: Picture, 'First Hearing' panel, from left: George Jellinek, Lloyd Moss, Martin Bookspan, Edward Downes and Robert Jacobson. By Gene Maggio-N.Y. Times