The first track on "Suzuki in Dub," one of two new recordings by the innovative Austrian duo Tosca, opens with a man whistling a light melody over some softly played, stately piano chords. Then a vibraphone enters, playing a solemn reverberating figure. This gives way to scat singing by a male vocalist, then the vibes return, accented by a scratchy rhythm guitar lick and joined by some gentle but intricate Latin percussion. Jazz? World music? Nope.

If you look for it at your favorite retailer or e-tailer, you'll find the recording in the dance-music area, possibly in a section set aside for a style called downtempo or chillout music. Music characterized by this austere layering of decidedly not in-your-face sounds has been growing into its own emerging genre. Some of its leading artists are selling well into six figures, small potatoes compared with Britney but astronomical for a niche music.

It started taking hold in the mid-'90s, almost in deliberate contrast to the hyperactive, frenetic beats of other dance-music styles like trance, big beat and industrial. Downtempo was serene and focused more on sensuous textures. Instead of the warehouse-size dance halls and big outdoor raves that nurtured the growth of rowdy uptempo dance styles, chillout grew in the swank hotel lounges and smaller clubs that look ready for their high-end interior-design magazine close up. However, even those who might have been put off by such upscale pretensions were lured by the music's sumptuous blend of sophisticated styles.

Typically, downtempo (a slight misnomer, as the "down" refers to a subdued mood more than the pace of the music) blends elements of dub reggae, bossa nova, jazz, some of Brian Eno's experimental rock or music of that ilk, and other artfully mellow sounds. And unlike most popular music, downtempo could withstand close listening or retreat into the background with equal ease.

Although chillout has avid followers in club capitals like London, New York and Tokyo, the music mostly developed far from the madding crowds in Vienna, northern England, Munich and Washington. It's nearly impossible to credit anyone with the invention of the style. But it was Austrians Peter Kruder and Richard Dorfmeister, Brits Steve Cobby and Dave McSherry -- better known as Fila Brazilia -- and D.C. locals Eric Hilton and Rob Garza, the duo known as Thievery Corporation, who popularized the sound. In a variety of full-length CDs and 12-inch vinyl singles, they applied their sonic prerogatives to many different and usually soulful tunes as remixers, before going on to develop their own material.

Fila Brazilia, Thievery Corporation and Tosca (which is a Richard Dorfmeister side project) are all releasing new recordings this winter that either point new directions for downtempo or reveal some of its roots. In addition, new recordings by the Icelandic singer Aria, the London duo Zero 7 and the New York-based Blue Six all expand the downtempo territory by incorporating its distinctive sound into other genres.

Initially, Kruder, Dorfmeister and others brought a distinctive tranquillity to their remixes. The Austrian duo's late-'90s collections, like "The K&D Sessions," and their "DJ Kicks" compilation went a long way toward popularizing the style. To create their own music, they separated, Kruder to form Peace Orchestra and Dorfmeister creating Tosca with his longtime friend Richard Huber.

In a dance-music demimonde that is a little too proud of its knob-twiddling aspects, Dorfmeister and Huber are clearly interested in highlighting their traditional musical antecedents. Dorfmeister reinforced the Puccini reference by naming one of the first Tosca recordings "Opera." Their two new releases, "Suzuki in Dub" and "Different Tastes of Honey," are remix CDs of material from their 1999 full-length "Suzuki," one of the classics of this new style.

Both discs showcase a series of the Austrians' colleagues and proteges working from a limited repertoire. "Different Tastes of Honey" is 13 remixes of the track "Honey." Although the tracks vary considerably in their approach to the tune, the repetition diminishes some of the pleasures. However, many of the recastings are sublime; the best one is Mossi's take on the song, which nestles a shuffle beat under the bass line and reduces the vocals to a minimal sample. Some remixes, however, blunt the nuance of the track by increasing the tempo to a house music gallop.

With reworkings of five different tunes and a stronger lineup of remixers, "Suzuki in Dub" fares much better. Most of the tracks are augmented by additional instrumentation and all of the producers keep to the minimalist aesthetic of downtempo. Eric Hilton and Rob Garza, the duo behind Thievery Corporation, met in 1995 at Hilton's Eighteenth Street Lounge in Adams Morgan. Introduced by a friend, the duo spent much of the evening talking about the legendary Brazilian composer Antonio Carlos Jobim. Although both make music with the latest technological gadgetry, they aim for the warmth and sensuality of bossa nova and early '60s jazz. Shortly thereafter, the two began collaborating on musical projects and got a key break when their "Shoalin Satellite" was remixed by Kruder and Dorfmeister on their "DJ Kicks" release.

Following three acclaimed Thievery releases, "Abductions and Reconstructions," "The Mirror Conspiracy" and their own entry into the "DJ Kicks" series, the Verve Music Group invited the duo to create a compilation from its vaults, which house the legendary jazz labels Verve, EmArcy, and Impulse! The result, "Sounds from the Verve Hi Fi," shows off the duo's inspirations. There's a bossa nova track by Stan Getz and Luiz Bonfa and a hot organ-soul jazz track from Jimmy Smith and Wes Montgomery. Even acid jazz, the early '90s club-based updating of '70s jazz-funk, gets a nod with a number from the Jazz Renegades. Although the selections occasionally border on cheese (Astrud Gilberto's cover of The Doors' "Light My Fire," for instance) by and large this compilation does an excellent job of showcasing Hilton and Garza's sonic fixations. It functions nicely as a seamless 50-minute tour of some overlooked sounds.

Cobby and McSherry first met in Hull in 1982, but they didn't begin working together as Fila Brazilia until 11 years ago. As a team they've established a reputation for chillout eclecticism. For instance, their remix clientele includes Radiohead, Busta Rhymes and Baba Maal. Through '90s recordings like "Power Clown" and "Luck Be a Weirdo Tonight," they established a sound based on a laid-back version of early-'70s soul. On their newest release, "Jump Leads," they range from bright instrumental tracks to minor-key, African-influenced songs. In general the music is sunnier than that of Thievery or Tosca; it's far more evocative of a weekend drive in the country than a 2 a.m. martini in a Rem Koolhas-designed space.

Yet Fila Brazilia's eclecticism is also its undoing. "Jump Leads" is far less distinctive than other downtempo music. The lack of a firmly established signature sound -- be it Tosca's dub-oriented atmospherics or Thievery's jazzy bossa nova -- makes it harder to get a handle on where the duo is going.

Other recent releases illustrate artists fusing downtempo's sonics with aspects of other styles. On its superb American debut, "Simple Things," Zero 7 (the London duo of Henry Binns and Sam Hardaker) creates an alluring mix of cinematic instrumentals with songs that borrow heavily from the jazzy sensibility of "Court and Spark"-era Joni Mitchell. On Blue Six's "Beautiful Tomorrow," New York house music producer Jay Denes damps down the often raucous party vibe into a cooler groove. And on "Haze," Aria blends her breathy soprano with Arabic grooves on some songs, slow synthetic beats to create a dreamy, ethereal sound on two other tracks, and a film-noir soundtrack approach to other tunes to create an impressively varied debut.

In some ways, downtempo's emerging appeal is easily explained: It brings to dance music the same sense of reserve that has made Sade an enduring pop figure and local legend Shirley Horn a must-hear for anyone interested in jazz singing. It's also one of the few styles that effectively blends recognizable older styles into something new and accessible. Last, with the pop world increasingly focused on teens and preteens, this style is unabashedly adult. Amid the growing panoply of dance-music styles, chillout has the potential to be with us for a while.

(To hear free Sound Bites call Post-Haste at 202-334-9000 and press 8151 for Thievery Corporation, 8152 for Tosca and 8153 for Fila Brazilia.)

Downtempo duo: D.C.'s Rob Garza and Eric Hilton of Thievery Corporation.