No one has written a rock opera about "1984," but when someone does, the Preview House would make a great setting for the last act.

The whole operation eerily resembles a NASA space-launch control. Housed in a darkened control room on the second floor of an imposing Sunset Boulevard building, staff members monitor a huge bank of computers, TV screens and data print-outs. The computer graphs glow like radium watch dials, their needles bobbing and weaving like miniature seismographs.

But here the technicians are listening for hit singles, not signs of Martian life.

The Preview House is the home of the little-publicized Audience Studies Inc. (ASI), a Hollywood market research firm that since 1974 has electronically measured responses to films, commercials, ad campaigns and new network TV programming.

Now rock 'n" roll has joined the roster too. ASI tests new singles for several major record labels, including Warner Brothers, Casablanca, ABC, A&M and Bearsville.

Industry insiders have credited ASI with predicting numerous major hits, including "Tonight's the Night" by Rod Stewart, "You Make Me Feel Like Dancing" by Leo Sayer, "Slow Ride" by Foghat, and several key Fleetwood Mac singles.

ASI's pitch to the music industry is deceptively simple: Minimize risks and maximize profits.For years, hit singles have been rock's most effective sales tools. It's almost unheard of these days to find a best-selling album that hasn't been propelled to the top of the charts by at least one hit single.

Yet ask music moguls to explain what makes a successful single and they mutter about instincts and gut appeal and hooks (the catchy melodies or phrases that make songs on the radio instantly recognizable).

Wasn't Rod Stewart's first hit an overlooked flip-side? Did Mick Jagger's crumbling marriage inspire the hypnotic appeal of "Miss You?" Who knows why teen-age girls swoon at the sound of Andy Gibb's latest 45.

Impatient with this guesswork, record companies constantly yearn for a more scientific approach. Some have turned to ASI's music research division, headed by veteran record man Larry Heller.

The 33-year-old music researcher is armed with a staff of market researchers, computer technicians and $3 million worth of state-of-the-art electronic equipment. The service costs roughly $600 per song. Clients receive results in a week, though Heller can rush out statistics in less than 48 hours. Heller now claims a 15 percent share of the Hot 100 and slightly more of the album charts.

His influence is even more pervasive. Mention ASI at a Hollywood music business gathering and you'd think an E. F. Hutton broker had just walked - everybody listens.

Twice a month, a special demographically-selected test group of 400 people between the ages of 12 and 35 crowd the Preview House's main auditorium. Heller attracts them with the promise of a free record and other prizes. He also carefully arranges the make-up of ASI's youthful audience, looking for avid record buyers, proper age and sex balance and a 25 percent sampling of blacks, who are found to be heavy singles buyers.

Everybody gets a recorder dial that registers five different degrees of interest, ranging from very good to very dull.

One new ASI research tool has sparked considerable controversy in the industry. To insure an unbiased response, Heller fits a sample of 100 people with tiny electronic sensors taped to their fingers. The devices monitor emotional involvement with the song by tracking the changes in their autonomic nervous system. This subconscious response is measured in terms of basal skin response (BSR).

This crafty technological wrinkle has outraged many music moguls. "It smacks of "1984,"" complained one record executive. "I'd like to think that our audience still falls in love with a record, not just gets a rise in their blood pressure."

Heller minimizes the role of the sensors, emphasizing that the physiological data merely supplements the audience's conscious responses. "We just take the audience's temperature. The sensors graph the difference between boredom and excitement," he said. "The data almost always replicates what we get from the recorder dial.

"BSR is still in its infancy. The technology is still far behind what our critics imagine the sensors can do. We don't even use them as a selling point to our clients." (This latter claim is not entirely accurate - ASI promotional brochures prominently display its BSR testing capacities).

Still, many moguls remain suspicious. "It's an important tool," said former Bearsville Records chief Paul Fishkin, a regular ASI client. "But is should confirm your feelings about a song. For Foghat, testing made all the difference in the world. I'd have to attribute the sale of 600,000 albums to ASI."

Another client, Russ Thyret, Warner Brothers director of promotion, also gave ASI mixed reviews. "I don't believe that playing a record for a relatively limited cross-section of our audience - a Southern California test group - tells us whether a song will be a hit," he said. "What it can do is tell us if it's not. So what I really look for from the tests are negatives - a song scoring badly means more than a song scoring well."

Another regular client added that the service doesn't account for timing, a key element in many pop record's success. "A ballad may get a great rating, but if Rod tstewart and Paul Mc cartney release new ballads at the same time, you're just not gonna do as well on the charts."

Central casting couldn't have sent over a more appropriate researcher. With his intense concentration, bearded visage and piercing eyes, Heller could play the scientist in any sci-fi movie. And the veteran researcher's attention to detail is worthy of the best set designer - Heller's testing operation leaves nothing to chance. He even hired a clinical psychologist to develop the dynamics of the session.

As each test group files into the lobby, they are serenaded with a tape loop of the singles' hooks so they'll be subliminally familiar with the melody of each test record. Heller plays a number of control songs to gauge the audience's reliability. (He also inserts some cartoons and a Mel Brooks short to loosen up the crowd.) His test sample is so consistent that nearly every group gives the control records exactly the same grades. "This is a lab environment," Heller said. "So we try to control as many of the variables as possible."

Still, to some record execs, no news is good news. "I'm only human," one label boss confided. "Who wants to hear that your golden boy's new song is going to stiff. I'd be depressed for days. That's the kind of advice I'd prefer to ignore."

It's no surprise that few clients boast about ASI's effectiveness. Satisfied customers have little inclination to brag about their triumphs to industry rivals. If anything, they often play down ASI's role, hoping to discourage their cronies from sampling its research wizardry.

This guarded attitude prevails inside the record company corridors as well. Record execs rarely offer any stirring ASI testimonials within earshot of their stars, whose fragile egos are bruised by the thought that a gaggle of teen-agers is judging their latest musical manifestoes.

Many record company promotion men also resent ASI's role in the starmaking machinery. Referring to a competitive testing firm, one veteran promo man complained, "If I'm forced to release what's picked by 50 kids wired to a machine, I might as well leave the business."

This is a prevailing sentiment. "There's a lot of resentment among artists and producers," Paul Fishkin said. "They all think you should go with your gut, not with sensors." Fishkin made no secret of Todd Rundgren's distaste for the testing service. Bearsville's top artist had a recent single that ASI figured should be edited for radio airplay. When Fishkin asked Rudgren to edit the song, he flatly refused.

Of course, you don't need ESP to tell Fleetwood Mac's fortune. But Heller can supply record labels with more sophisticated data.

He may advise which single should be released first or offer merchandising recommendations. ASI's space-age computer system also creates various demographic categories so that execs can determine exactly how well each age group, sex and race responds to their product.

"What's important is not the amount of acceptance," Hiller explained, "but where's it coming from." In simpler terms, this means that if a song has only male appeal, it may not do as well as a tune that enjoys more across-the-board acceptance.

Heller's findings dispel many pop music myths. His data shows that women enjoy raucous guitar solos as much as men. He also speculates that disco's most enthusiastic supporters are teen-agers, not the chic Studio 54 crowd.

Heller now is closely following an even more intriguing phenomenon - the new black disco backlash. He has found that many black listeners shun white disco tunes. "Songs that lack a soulful sound turn off the black audience," he reported.

ASI's research is no longer confined to rating records. Radio programmers compile playlists using ASI's test findings, while record labels have used the company's market research to plot ad campaigns and study changing record-buying patterns. Heller has already begun video testing for in-store promotion films and ad displays.

"We found that merchandising is critically important," he said. "You can sell at the point of sale too. If you can get the kids into the store to buy one record, odds are that they'll buy another one."

Heller refused to apologize for his heavy reliance on gadgetry and statics. "We just take the listener's pulse," he said. "We're not trying to change the music itself. That's for the kids to do." CAPTION: Illustration, no caption, by Juanita Mondello for The Washington Post