India’s Soundtracks Get Down, Dirty : Pop music: Trend dubbed ‘rustic raunch’ clashes with the official prudishness and hushed-up sexuality that have taken root in the land that once produced the Kama Sutra.

First there’s the rhythm line, as unsubtle as a panting steam locomotive. Then the singer’s sultry voice, earthy and suggestive: “What’s beneath my blouse?” Ila Arun croons temptingly. What indeed?

“My heart is beneath my blouse,” she warbles in reply to her own question. “And this heart, I will give it to my beloved.”

Grunge or gangsta rap it’s not. But Arun’s spicy Hindi-language tune about the secrets hidden by her choli , or bare-belly Rajasthani blouse, has become a controversial smash in India and brought a revolution in the usually staid, syrupy soundtracks of mass-market movies here.

“When you hear this music, you’re tempted to go see the film it comes from on the big screen,” Nandita Baruah, a New Delhi-based research associate, says enthusiastically.

To lure more members of her “MTV generation” to the theater, the 28-year-old Baruah says, Indian producers are now getting down and dirty.

Most Americans might not think so. But Indian cinema was once so strait-laced that it preferred to show a pair of doves contentedly cooing or two flowers blooming in time-lapse photography to symbolize the hero and heroine going into a torrid clutch.

Arun has shaken things up with a modernized and suggestive off-screen folk tune that helped make a hit out of the movie “Khalnayak” (“The Villain”) by being released beforehand as a cassette and a music video.

*

Seeing long lines form for “Khalnayak,” Bombay’s cinema barons took notice. “Going by the evidence, 1994 is going to be the year of smutty lyrics,” Amode Mehra, who helps compile and grade songs for a televised hit parade, has predicted.

Already on Indian screens, or reported to be on the way, are production numbers based on traditional folk ditties with these words, utilizing double entendres and pregnant pauses:

* “I am a train, please give me a push, my engine is hot, please give me a push. . . .”

* “I’ll put it . . . I’ll put it my darling . . . I’ll put a nine- lakh (900,000 rupee) necklace around your neck.”

(And this one, which uses metaphors from the sport of cricket:)

* “Yesterday my lover bowled such a torrid spell, I couldn’t sleep a wink all night; four times I hit the ball, the fifth I couldn’t handle.”

“These people think, if ‘Khalnayak’ could sell because of ‘Choli,’ then the public probably wants more,” Arun said proudly in an interview.

India Today magazine has christened the emerging trend in pop music “rustic raunch,” since it clashes with the official prudishness and hushed-up sexuality that have taken root in the land that once produced the Kama Sutra.

Some of the post-”Choli’ tunes are considered sufficiently risque to have been banned from All India Radio. But they circulate anyway on cassettes or in their video version on privately owned Zee TV. Some Indians think they epitomize a more relaxed attitude about sex, others, like Baruah, that they could be just a short-lived fad.

*

Folk tunes in regions of India like Arun’s native Rajasthan often have suggestive, even bawdy lyrics. Since the smash hit “Beneath My Choli,” she has gone on to sing a steamy video version of “Bicchu,” or “Scorpion,” which likens the first experience of physical love to the arachnid’s sting.

Her latest soundtrack shocker is from a movie called “Dalaal” (“The Broker”). With the male and female leads dancing and female extras lifting their saris archly in the background, Arun sings off camera: “He climbed on top of me . . . the pigeon on the terrace.”

The Bombay-based entertainer, who plans to tour California this summer, is proud to be reviving some of India’s less genteel traditions. She scoffs at the suggestion that her popularity means a decline in public morals.

“We Indians know how to have fun,” Arun said. “In Hindi, you know, you can’t judge a song by its first line. It’s the lyricist’s intelligence that can make you wonder.”