The Senate unanimously passed a bill late Wednesday to require television stations and cable companies to keep commercials at the same volume as the programs they interrupt.

The House has passed similar legislation. Before it can become law, minor differences between the two versions have to be worked out when Congress returns to Washington after the Nov. 2 election.

Ever since television caught on in the 1950s, the Federal Communication Commission has been getting complaints about blaring commercials. But the FCC concluded in 1984 there was no fair way to write regulations controlling the "apparent loudness" of commercials. So it hasn’t been regulating them.

Correcting sound levels is more complicated than using the remote control. The television shows and ads come from a variety of sources, from local businesses to syndicators.

Managing the transition between programs and ads without spoiling the artistic intent of the producers poses technical challenges and may require TV broadcasters to purchase new equipment. To address the issue, an industry organization recently produced guidelines on how to process, measure and transmit audio in a uniform way.

The legislation, sponsored by Sen. Sheldon Whitehouse, D-R.I., requires the FCC to adopt those recommendations as regulations within a year and begin enforcing them a year later. Rep. Anna Eshoo, D-Calif., is the driving force behind the bill in the House.

Its title is the Commercial Advertisement Loudness Mitigation Act, or CALM.

Sen. Charles Schumer, D-N.Y., a co-sponsor, said it’s time to stop the use of loud commercials to startle viewers into paying attention. "TV viewers should be able to watch their favorite programs without fear of losing their hearing when the show goes to a commercial," he said.