It's almost impossible to imagine Busta Rhymes at a loss for words.

The verbose rap veteran, famous for his mile-a-minute delivery, has been spitting rapid-fire hits for almost two decades.

But when filmmaker Byron Hurt asks Busta about homophobia in hip-hop, the rapper goes quiet.

"I can't partake in that conversation," he demurs. "With all due respect, I ain't trying to offend nobody. . . . What I represent culturally doesn't condone [homosexuality] whatsoever." When asked if a gay rapper could ever be accepted in hip-hop culture, Busta walks out of the room.

It's one of the most telling scenes in Hurt's first documentary for PBS, "Hip-Hop: Beyond Beats and Rhymes," airing tonight on "Independent Lens." The film aims to spark a dialogue about masculinity in a hip-hop culture that often embraces misogyny, homophobia and violence. From the looks of the film, it may not be a dialogue that the industry is ready to have.

Here's music mogul Russell Simmons on sexism in hip-hop: "I can't address every issue because I don't have the equipment."

Or BET executive Stephen Hill, on the hyper-masculinity in the music videos his channel airs:

"You should look at the people who actually make the videos."

And phenom rap duo Clipse on whether their lyrics reinforce violent stereotypes: (blank stare).

Despite the tough questions, Hurt isn't out to vilify the music he grew up with. The documentary begins with the 37-year-old director looking into his own camera to profess: "I love hip-hop." From New York, where he's based, Hurt elaborates, "I wanted to be clear with my audience about who I was. . . . I didn't want to be put in the same category as a Bill O'Reilly and the critics outside of hip-hop culture who don't have any emotional connections to the music."

For Hurt, those connections run deep. He remembers practicing his dance steps to a Fat Boys tune before going to his first party. During his days quarterbacking at Northeastern University in Boston, LL Cool J's "Mama Said Knock You Out" was the song that got him pumped up before game time.

After graduation, Hurt took a job working with young people in a program to prevent violence against women. It was then that he started to have mixed feelings about the music he loved. An afternoon spent watching stereotypical rap videos made the aspiring filmmaker realize, "It was a now or never sort of thing."

So he dove into a grueling fundraising effort and began interviewing rappers, activists, scholars and fans at national events like BET's annual Spring Bling celebration in Daytona Beach. "I wanted to make it a combination of real people and real events," Hurt says, "as well as the scholars and the experts who can speak very clearly to the issues."

The result paints a broad and eye-opening portrait of hip-hop masculinity. And while intellectuals Michael Dyson, Kevin Powell and rap legend Chuck D. offer sharp insights on male aggression, black animosity and homoeroticism in hip-hop, the most illuminating points come from the fans -- whether they're aspiring rappers at Spring Bling in Daytona or white teenagers trying to connect with the black urban experience in Moline.

When asked why so many aspiring rappers resort to violent imagery in their rhymes, one hopeful MC said that the record industry doesn't want to hear anything else. "They don't give us deals when we speak righteously," he shrugged.

There aren't many female voices in the film, a conscious decision by Hurt based on his experience in community work. "It was important for me to keep a male audience," Hurt says. "I know that boys are much more receptive to hearing guys talk about manhood. When they hear it from women they get defensive."

The film screened at last year's Sundance Film Festival to standing ovations. "It was incredible," Hurt says of the experience. "I sort of liken it to going to the Olympics. You get to meet filmmakers from all over the world. . . . My life hasn't been the same since then."

In other words, he's been busy. Hurt has been screening the film in schools across the country since Sundance, showing it as many as three times a week leading up to tonight's broadcast. Is he worried that he might not reach his intended audience on public television? "I think it's pretty accurate to say PBS doesn't appeal to the average hip-hop fan," Hurt says. "But it's unfair to say a hip-hop audience won't come to PBS. . . . People of color watch PBS when there's something relevant to them."

Yet for all its accolades, the film doesn't answer the question it has the courage to ask: How do we fix hip-hop? "One of the criticisms of the film is that it doesn't offer real solutions," Hurt says. "I did that intentionally. . . . I wanted the audience to take ownership over what can be done about this."

Hip-Hop: Beyond Beats and Rhymes (one hour) debuts tonight at 11 on Channel 26 (WETA).