A couple of years ago, researchers at the RAND Corp. released a study that found heavy exposure to sexual content on television shows relates strongly to teenagers' initiation of intercourse or their progression to more advanced sexual activities.

To some, those results seemed so reasonable because, well, aren't they so obvious? But there are always those who won't accept the obvious, even when it's presented for them on a scientifically documented silver tray. Critics were quick to argue that there was a chicken-and-egg question: Couldn't it also be argued that teenagers who are already predisposed to sexual activity have a predilection for sexier TV shows?

In the scientific sense, it is certainly possible that cause and effect may not be as simple as "monkey see, monkey do." But it's odd that some activists can berate corporations for tempting children into eating Twinkies and drinking sugary sodas, but then don't see corporations pushing hypersexual entertainment as tempting the young into premature sexual activity.

Now the RAND Corp. has a new study, published in the August issue of the journal Pediatrics, taking on another major teenage influence: their music. The same alarming results jump off the page. According to the study, based on interviews with nearly 1,500 teens, those who said they listened to sexually explicit music were almost twice as likely to start having sex within the following two years than those who listen to little or none of that music.

This holds true for boys and girls as well as for whites and non-whites, even after accounting for a list of other personal and social factors associated with adolescent sexual behavior.

Music is no small part of youngsters' lives. Adolescents typically listen to 1.5 to 2.5 hours of music per day, and that doesn't include the amount of time they are exposed to music through music videos. The researchers were especially concerned about sexually degrading music like the F-bombs and "ho" lyrics of the rappers.

"These portrayals objectify and degrade women in ways that are clear, but they do the same to men by depicting them as sex-driven studs," said Steven Martino, the RAND psychologist who led the study. "Musicians who use this type of sexual imagery are communicating something very specific about what sexual roles are appropriate, and teen listeners may act on these messages."

Martino and his research team acknowledge that some may argue that teens don't really listen to the lyrics of songs, or that listening to music is a passive and secondary activity for youth, but they also insist the sexual references in many popular songs may be difficult for them to ignore, because the language used to describe sex has become increasingly direct. They suggest a taste of the rap "artist" Lil' Kim: "When it comes to sex don't test my skills, 'cause my head game will have you head over heels. Guys wanna wife me and give me the ring. I'll do it anywhere, anyhow, I'm down for anything." They can then argue persuasively, "The interest in sex expressed in these lyrics is unlikely to be lost on many teens."

People who want to make excuses for the music industry also argue that sexual lyrics are nothing new in popular music, from "I Can't Get No Satisfaction" by the Rolling Stones to any number of songs that discuss "making love." But a lot of late 20th century music that played on the radio had a layer or two of euphemism or double entendre. It might have gone over the heads of grade-schoolers riding along in the car. That's not true any more. In fact, it's just the opposite today. These lyrics are as blatant as can be and are being marketed directly to young teenagers through the likes of MTV.

The RAND study also noted a recent analysis of the content of television shows, movies, magazines, newspapers and music popular among teens demonstrated that sexual content is much more prevalent in popular music lyrics than in any other medium.

David Walsh at the National Institute on Media and the Family argues that what music does is amplify. When we hear a patriotic tune, we feel more patriotic. When we hear a romantic tune, we feel romantic. When they hear a very sexually arousing tune, then is it any surprise that teenagers feel more sexually aroused and are more likely to act on it?

It's also unsurprising to note the best antidote to this onslaught is parental involvement. Parents need to be active in monitoring children's media diet and have frank conversations about what sex is, and what it should not be. Sadly, only 19 percent of American teenagers report that they have good communication with a trusted adult about sex. It's sad to think that the other 81 percent might be getting their sex education and social cues from filthy rappers and music videos, and the "pimping" corporations that profit from them.