ARRIVING AT the little old Georgetown home where Eric Barnouw, America's foremost broadcast historian, lives for half of each week, and having him witness the cough of a bad cold, one may be asked, "Are you taking any medicine you saw advertised on TV?" Told "no," Barnouw smiles and says "Good. I took a Dristan once, and I was never so sick in my life."

Barnouw, an awesomely active 70 now, doesn't believe in taking on sponsors for one-at-a-time, however. He believes in facing the gorgon, The Sponsor, itself. When he was researching by his new book, "The Sponsor: Notes on a Modern Potentate" (Oxford University Press), a network executive harrumphed., "The influence of the sponsor? Isn't that subject a bit absolete?"

That made Barnouw laugh, because he knows The Sponsor, like The Force, is always with us. They may not have a "sponsor's booth" any more, the way they used to in radio studios, but the commercial presence has anything but vanished, and it is present, significantly, in public TV and in TV news as well as in entertainment programming.

Barnouw wrote more, though, than a get-the-sponsor manifesto; in tracing commercial influence over broadcasting, he wrestles with and helps answer the central, nagging question of Why Television Isn't Wonderful.

It isn't wonderful, Barnouw says partly because the sponsor has almost always had his way. In TV and radio, creative and editorial decisions are made with"merchandising" considerations foremost in mind, producing a system "that has made the center of national attention a market item" and has put "the leadership of our society on an auction block." This isn't some old crank or media hysteric, either, Barnouw's credentials include years as professor emeritus at Columbia University and a long career in the dreaded realm of broadcasting itself. Every book he writes on broadcasting becomes the most indispensable work in the field since his last book came out, and that's the case with "The Sponsor."

"A sponsor who has the job of choosing whether to go with this program that reaches 42 million people of the 'right' age level," Barnouw says, "or with that program, which he thinks is a better program but only reaches 25 million people has a duty to his company to choose the poorer show. I do not think that our cultural life should be dominated by that kind of decision."

Where, exactly, did America make the great wrong turn on the pathway to the millennium?

"There are so many steps in the history of broadcasting that didn't seem significant at the time but later turned out to be very important," says Barnouw, while World War III, also known as the water department, digs up the Georgetown street outside. "For instance, when we allowed the sponsor to say, 'I insist on deciding on which program my commercial will be, then immediately we opened up a bargaining process over the price of the program so that you have, really an auction system. That was a fatal step.

"In Britain, on their commercial channel, there's a rate card, you buy a spot, and the broadcaster decides where to put it, not the sponsor. In Italy, they have an even broader segregation than that - solid commercials from 8:30 to 9 at night, and bargaining that has nothing to do with any particular program. Certain money comes into the network from those commercials and the network decides where to put it."

Our airwaves weren't always thick with pitches. In the early, genteel days of radio, commercials were sometimes mere mentions of a sponsor's name. The first code of the National Association of Broadcasters (NAB) actually stipulated that "Commercial announcements . . . should not be broadcast between 7 p.m. and 11 p.m." - the period later known as "prime time." When the stock market crashed and business went blotto, however, broadcasters and advertisers began to exploit the money-making machine that the government would, in effect, hand over to them.

A landmark in this learning process was reached on CBS radio when, Barnouw recalls, the president of the company that made Cremo Cigars authorized an announcer to shout at the radio audience, between numbers by the Cremo Military Bank, such boasts as, "There is no spit in Cremo!" Cremo sales soared.

Much later, live television's golden era of drama in the '50s was tarnished by nervous sponsors demanding script changes - like the gas company ordering all references to "gas" deleted from a play about Nazi concentration camps. Barnouw was working on a U.S. Steel Hour about a senator meddling in the affairs of a college when, during rehersals, the sponsor's representative declared the character would have to be changed to a governor "or people will think we're talking about (Sen. Joseph) McCarthy."

Barnouw want to remind us that the sponsor-run broadcasting system that made such things possible is not something God Himself ordained for the nation.

Commercial broadcasters would like us to think it is, since TV has made them monstrously rich.

"There's no other system that brings in the amount of money that ours does," Barnouw says. "And the greater the success, the more trouble we're in, as far as I'm concerned. Because it's only here in the United States that television has been so successful that politics has had to be fitted into the business of commercials. There isn't a single European country that has our system of selling time for political messages."

Barnouw sees no great hope for reform in such measures as the current congressional rewrite of the 1934 Communications Act still used to regulate broadcasting. "Television is so successcul and has such momentum, there's no chance to its being radically changed in the near future. I'm just amazed at the number of people who assume it wouldn't have been possible for it to be any other way, that whatever we have is probably inevitable and maybe for the best.

"The notion that we need more rules, more controls by the FCC doesn't work. The FCC has been virtually meaningless anywhere. What we need to do is liberate another set of motivations in television. When we had the anthology dramas in the '50s, and the initiative was really in the hands of writers who were writing what they wanted to write about, we were, for a moment, in a very good situation.A TV writer in Hollywood now is a terribly frustrated guy.He doesn't want to do what he's doing. When you talk to one, you find a terrible sense of frustration, a kind of rage."

But Barnouw still sees possiblities in public TV. "If we had a system financed the way Japan's is, we would have a public television budget that is something like 10 times as large as what we have. The effect of the BBC on the commercial system in Britain has been to make that system less commercial than ours. And the fact that Thames Television can do a thing like 'Upstairs, Downstairs' (oftenly wrongly credited to the BBC) is partly because they have a very strong noncommercial system."

New technologies - cable, pay TV recorders - are supposed to liberate us from the monolithic grip of commercial TV. Barnouw warns against premature hurrahs, however, because he knows the history of broadcasting - and wrote a definitive three-volume "History of Broadcasting in the United States" - too well. "I'm very skeptical about the euphoria that greets each of these new inventions," he says. "Take cable television; I think there's good reason to be alarmed at the idea that the whole country's going to be connected by optical fiber, by one system that can do everything. I think that's about the most perfect opportunity for control that anybody ever had."

As for euphoria over the new, "I think a Columbia professor who proclaimed years ago that television was going to make radion an intellectual medium, that it would liberate radio from the show-business razzle-dazzle and the word would be king again."

He laughs.Some joke. Indeed, people now wonder if TV isn't killing off literacy itself. "Some compare television to the printing press," Barnouw says, "but as Daniel Boorstin has said, the printing press never could influence anyone until they had learn to read. During you most vulnerable years you were sheltered from its influence. Today you have a kid in the 'cradle already watching television - bypassing his parents, his grandparents, church, school, everything, and the parents are generally willing to let TV take over.

"I just read in a scholarly journal that television is going to bypass the whole literacy 'problem.' We'll no longer have to discipline people in order to get them to learn; they'll be educated purely by the attractiveness of it all. It's a little frightening. I visited a junior college a few weeks ago and in the library I saw desks and desks of people studying tapes and films and discs, and the professor guiding me around said, "This is very necessary, because the reading level here is at an 8th-grade level; so we're bypassing that problem.'

"Eventually, this kind of thing will create an elite class who can read and they will interpret the past for other people through docu-dramas and so on. The past will not exist except as mediated by them. And so we'll have a continual revising of history - which is a bit like '1984.'" He smiles."And we'll get it right on schedule."

Barnouw somehow manages to write not only knowledgeably but jauntily about gloom and doom through television. Still, he doesn't always leave 'em laughing. In "The Sponsor," he recalls the prediciton of Arnold Toynbee that electronic media will produce "a parasitic society which, like the urban proletariat in the Roman Empire, lives for 'bread and circuses' and turns savage if it is not given to them."

Barnouw calls welfare and television the modern equivalents to bread and circuses - "pacifiers of empire, protectors of power and privilege."

Ironically or not, Barnouw is hitting the TV trail to plug his book.He's already done a few interviews, including one at the CBS station in Kansas City, where the interviewer told him ahead of time she planned to aska, "Don't you think the sponsor is really a necessary evil?"

When they got on the air, though, she asked instead, "Don't you think the sponsor is really necessary?" Later she explained to Barnouw, "I wanted to keep my job." They all do.