It's no secret that reggae, the contemporary music of Jamaica, is an outgrowth of New Orleans R & B. After World War II, Jamaicans began listening avidly to American radio, especially to hear urban blues singers like Louis Jordan and Amos Milburn. As a result, an unusual type of entertainer was born in Jamaica -- the Sound System man. He would rent dance halls and play loud R & B records from the U.S., especially New Orleans, an accessible city overflowing with brash, danceable music.

While turbulence blasted from the speakers of men like Prince Buster and V-Rocket, the dance halls started promoting local groups in addition to the deejays. Surrendering to the new competition, the Sound System men quickly created an alternate industry by recording these aspiring musicians. Their early records were essentially crude imitations of the New Orleans R & B sound, featuring tenor saxes, trumpets or trombones, boogie piano, and bass.

By 1962, the bass became the prominent instrument on Jamaican recordings, the rhythm shifting to a strange shuffle accentuated on the offbeat by the rigid riff of the brass. This riff was referred to as "Ska," and the term stuck as the generic name for the musical form itself. (However, in England, the music acquired its name "bluebeat" from the first record label to feature the style -- Melodisc's Blue Beat.)

Since 1962, Jamaican music has undergone two significant transformations -- rock steady in 1966-67 and reggae in 1968. Currently, the unsurpation of the style by British rock 'n' roll bands, whether in the stormy manner of the Clash or the watered downmimicry of the Members, could lead to another change within the genre --"reggae rock," certainly not as raw as pure Jamaican music but every bit as refreshing.

At present, the English band most adept at blending the big beat of rock with reggae rhythms is the Specials, a ragged gang of five Lean skinheads and two tough-looking blacks.

The band's racial integration does help give their image an authentic edge; yet there are precedents in British pop history of whites and Jamaicans uniting to record a hit record -- the Equals ("Baby, Come Back") and the Foundations ("Build Me Up Buttercup"). The Specials' distinct historical contribution is their marriage of rock with reggae, without compromising either unlike other experiments with this recent hybrid.

Their debut album, "The Specials" (Chrysalis CHR 1265,) is a powerful example of a rock band's putting the final squeeze on the trigger of rebellion. Produced by Elvis Costello with his ears open to every sparse syllable and tiny twitch, it summons forth the hollow panic of a concrete jungle's helpless inhabitants.

The album opens with "A Message To You Rudy," a call for all rude boys and girls to pay attention to their social duties ("Stop your messin' around -- Better think of your future"). In fact, the Specials are addicted to this theme --"It's Up To You" (a sermon employing the dub homiletics of U-Roy), "Too Much Too Young" (a scornful diatribe against teen-age pregnancy) and "Stupid Marriage" (a divine comedy a la the antics of Pigmeat Markham).

The Specials speak to the modern world both through glorification ("Dawning of a New Era") and existential gloom ("Blank Expression") -- but especially through reinterpretation. They trasform Rufus Thomas' "Do the Dog" into an ecumenical embrace, and their version of Toots and the Maytals' "Monkey Man" is as soulful as the music of the Maytals' own god, Otis Redding.

Thanks largely to the Specials, Madness has also released a debut album, "One Step Beyond" (Sire). Madness' first single, "The Prince" (a tribute to ska performer Prince Buster), was originally distributed by the Specials' own label, 2 Tone.

Madness consists of six oddballs and one dancing geek, all fugitives from the Daffy Duck Asylum for the Truly Deranged. Their album is a wacky pastiche of ska, British tradrock, and progressive doodling. Be forewarned: Madness does go to rather silly extremes to get attention. Consider their demolition of Swan Lake."

Goofier still is their ode to Alvin and the Chipmunks entitled "Chipmunks Are Go!" -- a chant for nutty cheerleaders: "1, 2, 3, 4! We're the chipmunks, hear us roar!"

Unfortunately, there are actually only two cuts on the album where Madness really roars; both are genuine attempts to re-create the primitive sound of ska performers. "One Step Beyond" begins with a thunderous rap that combines comedy with seething hysteria (" . . . so, if you've come in off the street and you're beginning to feel the heat, well, listen, Buster you better start to move your feet . . ."), and "Madness," originally recorded by Prince Buster, captures an authentic feel for ska's simple riff, becoming an instant anthem for this gaga novelty band.

"Intensified! Orginal Ska 1962-66" (Mango MLPS 9524) is a priceless collection of the rough music that inspires Madness' brand of insanity; in fact, the orginal genre is 10 times crazier than Madness' ersatz sound.

"Intensified!" isn't strictly for musciologists, however. True, it is a historical treat to hear the influence of Shirley and Lee on Derrick and Patsy's "Housewives' Choice" or the unprofessional grace of early recordings by current reggae stars like the Maytals and Justin Hines.

But there's also a demented side to this music that's exemplified on songs such as Eric Morris' "Solomon Gundie," Tommy McCook's "Rocket Ship" and Baba Brooks' "Duck Soup." These are classic records which, with their kooky noises and strange sound effects, stand for nothing but meaningless fun.

In America, it is virtually the Mango label alone that's keeping Jamaican music alive. Mango release records that pop bands like the Specials and Madness can only dream about making.

An exceptional new release on Mango is Burning Spear's "Harder Than the Best" (MLPS 9567), a compliation that mixes the highlights of the band's previous six albums into a compelling and comprehensible whole, a monumental work that easily ranks with Toots and the Maytals' "Funky Kingston" or the soundtrack to "The Harder They Come." This is reggae with a burning purpose, and Mango deserve a string of pearls for continuing to release such forceful music.

Even without Mango's support, though, reggae's spirit will never fade away. As the liner notes to "Intensified!" state (the words composed by the mysterious Mr. Johnnie Cool): "But time is longer than rope and this is the sound that goes around."