A report by the US Government's Federal Trade Commission (FTC) said that the music industry, unlike the film and video game industries, had made little progress since its last study in September 2000.
The FTC found that advertising for what it called "explicit-content labelled music recordings" routinely appeared in popular advertising for teenagers.
It said that all five major music companies placed such advertising in media with substantial under-17 audiences.
Progress
When 'parental advisory' stickers were present on advertisements, they were frequently so small as to be illegible.
The FTC reported that the film and video game industries had "made some progress both in limiting advertising in popular teen media and in providing rating information in advertising."
The report says that the FTC continues to favour what it calls "vigilant self-regulation" rather than government action.
"Unfortunately, the music industry response, at least so far, has been disappointing in its failure to institute positive reforms to its self-regulatory structure," the report said.
Bill
The FTC reports on the entertainment industry were commissioned by former President Bill Clinton after the massacre in April 1999 at Columbine High School in Colorado, which heightened concerns about the effect of violent entertainment on young people.
Democratic Senator Joseph Lieberman is expected to introduce a bill later this week aimed at punishing firms that market violent media products to children.
Lieberman has been a vehement critic of the US entertainment industry for what he has called "routinely and aggressively marketing adult-rated material to children".
His bill, co-sponsored by Wisconsin Democratic Senator Herbert Kohl, would give the FTC powers to take action against companies that marketed such products under their "false and deceptive advertising" rules.
Critics of Lieberman's proposals say that the move would amount to cultural censorship and is contrary to the US Constitution's First Amendment rules protecting free speech.
Marketplace
On Monday, the Motion Picture Association President of America's chief executive Jack Valenti vigorously invoked what he called the "glorious Amendment" to defend free speech.
Speaking to a broadcasters' convention in Las Vegas, Valenti said, "You must allow that which you judge to be meretricious, squalid and without redeeming value to enter the marketplace."