If you turn on a radio and sample dozens of stations, you may not think much of what's on the air. The commercialism and lack of diversity are apt to seem normal. But it didn't have to be this way.

Sixty years ago, in May 1934, a hard-fought battle reached the floor of the U.S. Senate. Lawmakers debated the future of broadcasting. The result was the landmark federal Communications Act.

Today we take it for granted that the finite space on the radio dial is dominated by large corporations. Even on "public radio," where the sponsors are called "underwriters," big bucks largely determine what will be heard.

But when radio was very young, few people assumed that "the ether" should be turned over to companies pursuing private profit. As late as 1928, even the interim Federal Radio Commission acknowledged that "advertising is usually offensive to the listening public."

That commission routinely sided with CBS, NBC and other new radio giants -- while cutting the hours and watts of nonprofit stations run by colleges, labor unions, religious groups and civic organizations. Those nonprofit broadcasters were some of radio's pioneers.

As the feds "reallocated" radio frequencies, the nonprofit stations steadily lost out to the "chain stations." By 1931, over 90 percent of the stations broadcasting at 5,000 watts or more were affiliated with a national commercial network.

Some big stations -- such as WGN, owned by the Chicago Tribune -- got "clear channel" licenses to broadcast at 50,000 watts. And, as corporations grabbed the airwaves, annual revenues from radio advertising soared-from peanuts in 1927 to $100 million in 1930.

"Never in our history has there been such a bold and brazen attempt to seize control of the means of communication and to dominate public opinion as is now going on in the field of radio broadcasting," said the director of a station operated by the Chicago Federation of Labor.

Also battling the radio trusts was a small order of Catholic priests, the Paulist Fathers, based in New York. Their station, WLWL, often provided working-class listeners with discussions of social issues. Federal authorities squeezed WLWL's broadcast hours, contending it was a "special interest" station.

That infuriated the Rev. John B. Harney, who fired back that WLWL was "not a special interest, unless you want to say that those who are working for public welfare are pursuing special interests and that the gentlemen who are working for their own pockets are not."

Resentment toward audio hucksters was widespread. Blaring commercials were new -- and jarring. In 1932, Business Week magazine declared: "Radio broadcasting is threatened with a revolt of listeners.... Newspaper radio editors report more and more letters of protest against irritating sales ballyhoo."

Two years later, renowned educator John Dewey warned: "The radio is the most powerful instrument of social education the world has ever seen. It can be used to distort facts and to mislead the public mind." He continued: "Whether it is to be employed for this end or for the social public interest is one of the most crucial problems of the present."

Activists built a radio reform movement, with petitions and newsletters and lobbying drives, to resist the broadcast monopolies. But most print media were unsympathetic.

The scant coverage that the press devoted to the radio reform battle was usually slanted in favor of the broadcasting companies. By the early 1930s, many newspapers had gained major holdings in profitable radio stations.

And quiet deals were cut in high government places. One factor: Many politicians, from President Franklin Roosevelt on down, were dependent on radio networks to carry their speeches.

Drew Pearson and Robert S. Allen got it right in their "Washington Merry Go-Round" column on Nov. 30, 1933: "A secret move is on foot to perpetuate the present monopoly which the big broadcasting companies have on the choice wavelengths."

Aided by the Roosevelt administration and allies on Capitol Hill, corporate broadcasters were able to usher in the Federal Communications Commission -- still in existence today -- established by the Communications Act of 1934.

Just before the Act's passage, the New York Times ran the headline "New Communications Bill is Aimed at Curbing Monopoly in Radio." The truth was just the opposite.

The Act stands as a monument to corporate power in U.S. broadcasting -- and as a tombstone for democratic use of the airwaves.

In a last-ditch effort to head off radio monopolization, a grassroots campaign sparked by church and labor activists lobbied to set aside 25 percent of radio frequencies for nonprofit broadcasters. The measure was known as the Wagner-Hatfield amendment.

Commercial broadcasters fought back fiercely, and successfully. The Wagner-Hatfield amendment lost, 42-23, in the Senate. This defeat of public-interest forces in 1934 set the stage for private-interest control of American television later on.

All of this hidden history is excavated by scholar Robert W. McChesney in his meticulous new book, "Telecommunications, Mass Media, and Democracy."

The radio reform movement was thwarted by the great extent of corporate media control that already existed. As McChesney notes, "The network-dominated, advertising-supported basis of U.S. broadcasting was anything but the product of an informed public debate."

After 1934, he points out, "Congress would never again consider fundamental structural questions in its communications deliberations. The legitimacy of network-dominated, advertising-supported broadcasting was now off-limits as a topic of congressional scrutiny."

Today's Congress remains uninterested in questioning corporate control of the airwaves that are supposed to belong to us all.