LOS ANGELES - Shush, already. That's the message the Federal Communications Commission is sending with new rules that force broadcast, cable, and satellite companies to turn down the volume on blaring TV commercials.

The FCC passed a set of regulations Tuesday that will prevent commercials from being louder than the shows around them. It's all part of the Commercial Advertisement Loudness Mitigation (or CALM) Act, which President Obama signed into law last December. The rules go into effect a year from now. Companies that do not comply will face unspecified FCC action.

Thunderous television ads have annoyed viewers for years. The FCC says people have grumbled about the issue for at least half a century. But since 2002 loud advertisements have been one of the top complaints the FCC receives.

And since the conversion to digital TV broadcasts two years ago, loud ads no longer take up more airwave space than quiet ones. The change transformed the commercial break into a noisy arms race.

"Nobody wanted to be the quiet guy in the set of commercials," says David Unsworth, senior vice president of satellite and technical operations at DG, a company that distributes ads to broadcasters.

In a recent analysis, DG found that some ads were 10 times as loud as the programs they interrupted.

"Everybody's been trying to push the envelope using [digital] compression to make their spots as loud as they can," Unsworth says.

A few years ago, an annoying ad got to the ears of Rep. Anna Eshoo, the Democratic congresswoman whose district in California's Silicon Valley is home to Facebook and Hewlett-Packard Co. While watching a sporting event with family members, Eshoo was jarred by a "horribly loud" commercial. Her brother-in-law suggested she do something about it. She did - with what started as a simple, one-page legislative proposal.

The measure became one of the most popular bills she has ever sponsored.

"What I never dreamed of was what kind of chord it would strike with people," Eshoo says.

The FCC rules require TV distributors to set up equipment to monitor the average sound level of ads as they come in. If they are too loud, distributors must adjust the sound levels before they can be aired. It recommends practices set out in 2009 by the Advanced Television Systems Committee, a standards-setting body.

If compliance with the rules places a financial burden on a company, the FCC will give it extra time - up to December 2014 - to comply.

Those concessions have helped to reduce opposition.

"We think that the FCC struck the right balance," National Association of Broadcasters spokesman Dennis Wharton said.

ABC says it already has installed equipment at its eight television stations. CBS has been operating under the guidelines for some time. NBC has sent specifications to its commercial suppliers and has installed equipment to reduce the volume of loud ads. Fox declined to comment, although Unsworth says the network has been rejecting ads that are too loud and getting advertisers to fix them.

Leading cable TV companies Comcast Corp. of Philadelphia and Time Warner Cable Inc. declined to comment.