After 40 years and countless talent-free performances, it is hard to imagine how revolutionary bossa nova must have sounded to North American ears.

But while that initial surprise is impossible to recapture, several recent releases serve as reminders of the richness and continuing relevance of this music. Call it the power of whisper.

Bossa nova exploded in the United States in the early 1960s, a time of transition in pop music and jazz. Tin Pan Alley and the Great American Songwriters were sounding their age, while the Beatles and Motown had not yet emerged. In jazz, the hard-bop wave had crested. Even the Latin market was in flux -- Fidel Castro's revolution had dampened the American ardor for Cuban music, leaving room for sounds from other Latin countries, preferably non-communist ones.

Into this setting came the quiet swing of guitarist Charlie Byrd and saxophonist Stan Getz in "Jazz Samba," the seductively artless singing of Astrud Gilberto in "The Girl From Ipanema" ("Garota de Ipanema"), and the rest of the bossa nova invasion. It was a modern, hip sound that spoke in sighs, easy on the ear but coolly sophisticated, exotic but also somewhat familiar. Better yet, there was substance to all that style.

In its words and melodies, bossa nova was music of deep lyricism. Rich, complex harmonies -- often drawn from the impressionists, some via cool jazz -- were elegantly set up in deceptively simple sequences. Rhythmically, bossa nova often suggested samba, but with the thunderous drums of Brazil's famed samba schools replaced by soft, syncopated chords plucked on the guitar.

Bossa nova became a worldwide rage. The fad eventually passed, but bossa nova's influence remained.

Two recently released recordings from the early '70s by poet, diplomat, journalist and Bohemian extraordinaire Vinicius de Moraes -- the most important lyricist in bossa nova -- are fascinating musically and as period pieces. De Moraes, known throughout Brazil simply as "Vinicius," had already made his mark as a writer before he collaborated with composer Antonio Carlos Jobim on classics such as "Chega de Saudade," "Insensatez" and, of course, "Garota de Ipanema," one of the most-recorded songs in history.

There was an actual "girl from Ipanema" -- Helo Pinheiro, who used to stroll down Montenegro Street in Rio de Janeiro on her way to the beach. Her route took her past the Bar Veloso, where Vinicius and Jobim used to spend long, liquid hours at a table next to the sidewalk. Their ode to the lovely Heloisa became a classic, Helo became a Brazilian celebrity, and Montenegro Street is now named "Vinicius de Moraes."

In the 1970s, Vinicius embarked on a career of his own as a performer that lasted until his death in 1980. His main collaborator was his friend, guitarist and songwriter Antonio Pecci Filho, nicknamed Toquinho, with whom he went on to record 20 albums. They made for a peculiar but engaging act.

Toquinho provided the musical accompaniment and played straight man to Vinicius, who would talk-sing seated on stage, often installed behind a small table, sipping whiskey. Frequently, to round out the show, they would also invite a guest singer. Released a few months ago for the first time in the United States, "Live in Buenos Aires" (Circular Moves), featuring Vinicius, Toquinho and singer Maria Creuza, is a period classic.

It was recorded in 1970 and released originally in Argentina as "Vinicius de Moraes en 'La Fusa' " -- the title refers to a popular club in Buenos Aires where they had a successful run, but it turns out that the album was actually recorded over two nights at a local studio before an invited audience. (It also features an Argentine rhythm section.)

According to Vinicius's own notes, applause and ambient sound from the nightclub were added in post-production. Whatever. Even more than 30 years later, classics such as "A Felicidade," "Canto de Ossanha," "Eu Sei que Vou Te Amar" and, of course, "Garota de Ipanema" retain a marvelous mix of warmth and freshness. Beyond the rich musical elements, there's a humanity to bossa nova that makes it transcendent. That essence was captured here perfectly.

"Days in Mar del Plata" (Circular Moves), with Vinicius, Toquinho and singer Maria Bethania, is not quite as compelling but still a worthy follow-up. Just as the original was not recorded live at the club, "Days in Mar del Plata" was not actually recorded at the Argentine seaside city, where they were performing at La Fusa's summer location, but at a studio in Buenos Aires.

Still, the performance has a loose, spontaneous feel, with Vinicius introducing some of the tracks with commentary (as in "Samba da Bencao" or "Tarde Em Itapoa") and taking time to recite a poem. Bethania, then at the beginning of her stellar career, sings on just five of the 11 tracks, her deep voice and melodramatic style offering a useful contrast to Vinicius's light and casual approach.

The playing is tight and sharp but low-key (this recording also features Argentine players added), and the sound is, as in the original, smartly unpolished. The overall effect of these discs is like hanging out after hours at someone's home -- and these guys can sing and play. Pull up a chair.

Singer, guitarist, composer and producer Celso Fonseca is the proverbial overnight success 20 years in the making. He turned a stint as guitarist for singer and songwriter (and current minister of culture) Gilberto Gil in 1981, into work with major Brazilian pop figures such as Chico Buarque, Milton Nascimento, Caetano Veloso and Gal Costa.

In 1986 he moved to the control room side of the recording studio, working as producer for artists such as Gil, Vinicius Cantuaria and Virginia Rodrigues. "Natural" (Ziriguiboom/Six Degrees) is Fonseca's sixth album under his own name and, like the classic recordings of bossa nova, a style in which his music is obviously rooted, it's smooth, smart and casually sensual.

Backed by a small group, Fonseca's singing rarely needs to rise above the intimate whisper to make its points. He sets the tone in the opening "Bom Sinal," where the relaxed playing and singing puts the listener in the middle of the lazy summer day of the first line in the Portuguese lyrics ("it's summer again, it's hot and I'm crazy to see you"). In the best bossa nova tradition, he sings "The Night We Called a Day" (in English) with a hint of regret but undramatically, which underscores the feelings in the lyrics. And one can hear his smile as he sings the classic Jobim-Vinicius "Ela e Carioca," a flirty song of praise to the women of Rio de Janeiro, sung in English and Portuguese.

The songs, nine of the 12 by Fonseca, unfold with an elegant logic and so does the arranging: The instrumentation is subtly layered and the details reveal themselves only after repeated listenings. As for grooves, and in the less-is-more spirit of early bossa nova, Fonseca sets the beat with his guitar playing or uses light percussion to imprint tracks such as "A Origem da Felicidade" or "Meu Samba Torto" with a discreet but irresistible forward drive.

It all sounds so easy.

(To hear a free Sound Bite of Vinicius de Moraes, call Post-Haste at 202-334-9000 and press 8185.)

Two recently released recordings from the '70s by lyricist Vinicius de Moraes convey bossa nova's seductive charm.