NEW YORK — Despite a double-digit sales slump and mounting public criticism, rap has not lost its ability to create monster hits — but the fresh-faced artists who make them seem to disappear by the time the next smash registers on the charts.

From Soulja Boy, whose "Crank Dat" has topped the pop charts for the past six weeks, to Mims and his No. 1 "This is Why I'm Hot" from earlier this year, a new generation of rap stars are sustaining the genre with huge party jams that take over the radio, Internet and especially cellular ringtones.

For the most part, however, what these artists haven't been able to sustain is their own success.

"They're not making substance material — they're not really going into creating a sound," complains the rap veteran Snoop Dogg.

"It's all about making the hot song for right now, but the artists who will stand the test of time like myself are about making records, not songs," he added. "You got to make a quality album so you can hold people's attention. It's like a movie. If you make a movie that got (only) one good scene, ain't nobody gonna go see it."

Acts like Dem Franchize Boyz, a group on Virgin Records (a division of EMI Group PLC), have definitely caught America's attention — "Lean Wit It, Rock Wit It" was the party jam du jour last year — but they aren't on the charts today. And they're not the only ones.

Young Dro, on Warner Music Group Corp.'s Atlantic Records, had everyone doing the "Shoulder Lean" last fall, and his ringtone sold more than two million copies. He hasn't had a top 10 hit since. And while Rich Boy's "Throw Some D's" was so potent even Kanye West did a remix, the Interscope artist has been pretty much M.I.A. on the charts since then. The ringtone went platinum, but Rich Boy's debut album has sold only 354,000 copies.

Not that record labels necessarily have a problem with all that, especially when those artists are racking up huge ringtone sales — most of which sell for about $1.99 for a snippet of a song, compared to 99 cents for a whole song on iTunes.

"That's just a business mind-set for the record companies ... instead of artist development, they're looking for that," says Jermaine Dupri, president of urban music at Island Records. "It makes the record companies not want to artist-develop the groups anymore because that's what they're into — they want to try and sell as many ringtones as possible."

Mims, another Virgin Records act, was huge on the ringtone market and the pop charts, with "This is Why I'm Hot." The slick street anthem shot to No. 1 and was a platinum ringtone. But the album only sold 290,000 copies and Mims has yet to have another hit — which one veteran act finds troubling.

"He doesn't have another one? At least one more?" 50 Cent said in a recent interview, blaming it on the lack of artist development on the record label's part. "And then you're surprised that people don't want to spend their money on CDs anymore?"

"In today's music business, (fans) buy singles of songs that they like but they buy albums of stars that they love," says "Big" Jon Platt, a top executive at EMI Music Publishing. "There would be a time back in the day where you would know everything about an artist. Today you don't know what half of these artists look like."

But it's not only record labels who are looking for ringtone raps to boost their coffers. Some in the industry blame rappers who are increasingly whipping together simplistic, catchy songs aimed at the ringtone market.

"About one or two weeks ago, one of the saddest things happened to me, when (an artist) played me a record and said, 'This would make a hot ringtone,"' said Platt, president of west coast creative at EMI.

"Right now the state of where we are at in hip-hop, it's different," 50 Cent says. "I don't think they want the lyrics to be complex — they want it to be simple, catchy. The Southern-based artist can be credited (with) that, because they're dancing, so now your record has to pretty much be catchy. It doesn't have to be super content, extreme content. It has to have a good rhythm to it and dance."

Seventeen-year-old Soulja Boy says that's what people want to hear these days.

"People don't want to go to a club and hear (about) people getting shot or hear about your life story," he says. "People want to ... have fun and dance and party."

Still, Soulja Boy, on Interscope Records (a division of Universal Music Group), knows about the pitfalls of some of his predecessors, and is hoping not to fall into their lot. Already, he's got a song "Soulja Girl" rising on the charts.

"When I did my album, I went into the studio (thinking), 'I gotta have each song on here where it will be good as a single,"' he says. "I believe I came out with an album full of singles, so I'm good."

Though Dupri admits that there have been times when he's signed an "ringtone act" (Dem Franchize Boyz were his group when he was president of urban music at Virgin), he says there needs to be a balance between acts signed simply for ringtone success and long-term prospects.

"You have to try and play both sides of the game," he says.

But for all the concern about what the future holds if the industry focuses on ringtone rap stars, Platt sees an even more worrisome aspect of their success.

"If it wasn't for these singles blowing up, and some of the digital downloads and the ringtones, it's kind of scary of where the business would be at this point," he says, noting the rap genre's 21 percent sales dive in 2006. "It's a Catch 22. It's not selling albums, but it is helping drive the genre further because there's been no big (new) artist to carry it."