Boston Globe, March 23, 2007

NEW YORK—When fully expressed, the human voice has such potential that instruments are crafted to imitate it, not the other way round. In fact, whole traditions of music honor the voice above all other instruments. Seen this way, a song can be a terribly limiting thing. Verses and refrains shackle inventiveness. Lyrics force subtle shadings of tone into foregone conclusions, constrained by language and vocabulary.

That’s just one way of looking at things, of course, but it’s enough to have bred a stream of jazz musicians who use their voice to interpret mainly wordless compositions. It’s a different technique than scatting: In wordless singing the voice harmonizes with the other instruments, improvises, maybe takes a solo. It’s hard to do, and when done poorly, can be quite a drag.

Now a young singer and composer who has embraced the technique to great effect is emerging on the Boston scene. Sara Serpa was the featured guest of saxophone great Greg Osby during a recent Berklee residency. Wednesday, she takes the stage at Ryles as the leader of her quintet.

Serpa started in her native Portugal before coming to attend Berklee and is now earning a master’s degree at the New England Conservatory. At 28, she’s a shade older than many of her classmates. She’s released an album in Portugal and performed extensively there.

She doesn’t yet have a US album but some of her work with the current quintet can be found on her MySpace page. It’s an airy, unhurried music, foregrounding the interplay among Serpa, guitarist Andre Matos and pianist Vardan Ovsepian. As tracks like “Praia” or “Space” open, the three weave in and out of each other’s notes in a kind of stylish hide-and-seek before Serpa takes her solo to establish the piece.

Serpa draws some of her liberty from not having started off as a singer – nor even, she says, in jazz. She began piano at 7 and went to a Lisbon conservatory at 11 as a pianist. Then came classical singing, and only later, in her 20s, jazz. As she literally found her voice, she remained fascinated by improvisation.

“Since I started doing jazz I’ve always wanted to do difficult things, challenging things,” she says over a cup of tea. “The challenge for me was to understand how instrumentalists play and improvise. My goal was to understand what they were talking about.”

Wordless singing was the natural way to develop this interest: “My voice is another instrument, with its own color. Lyrics give a very specific mood to songs. I choose not to use words, but music is a universal language. I’d rather use words when they mean something to me.”

That’s not to say you won’t hear words in Serpa’s music. She performs the occasional standard – “reharmonized and rearranged,” she says, “to make it a little bit more my song” – and she enjoys working with pieces of Portuguese poetry. Reasonably enough, though her English is excellent, she’s most comfortable dealing in her mother tongue.

“I’m not a native English speaker,” she says. “Sometimes expressions make more sense to me in Portuguese than in English. For instance, I can feel a Brazilian song much more deeply than an English song.”

Still, it’s the wordless improvisation technique that really stands out in Serpa’s work and that garnered the attention of Osby, a noted talent-spotter who groomed in his band such new-school masters as the pianist Jason Moran and vibraphonist Stefon Harris.

Serpa says she and Osby met in classic 21st-century fashion: online.

“About a year ago, I got a message from him on MySpace saying he was interested in my music. I don’t know how he came across it. I sent him some songs and we kept in touch.”

They discussed music and collaborated via e-mail, and finally met in person last month during Osby’s residency at Berklee. Playing as his guest with a Berklee ensemble was, Serpa says, “a great experience. It was extremely challenging. I had to be on the spot.”

Serpa is far from a stage novice, however. On her trips back to Portugal, she performs frequently at various clubs. She is also emerging on the festival circuit, which flourishes in Portugal like elsewhere in Europe thanks to public funding. This year, she will appear for the first time at the Festa do Jazz, a prestigious festival that showcases domestic talent by requiring that all performing groups have a Portuguese leader.

The Portuguese scene is still small, Serpa says, but tight-knit and growing. The country recently opened its first jazz-focused conservatory, in Porto. Many of Serpa’s American-trained Portuguese musician friends were happy to return home quickly, not least for the quality of life: the weather, the atmosphere, the less frenetic work pace.

Serpa’s plans are different. She intends to wrap up her master’s degree next year and head to New York to build her career in the American market. With her distinctive voice, assiduous work habits, Boston educational pedigree, and collaborations with national figures like Osby, there’s plenty of reason to believe that she’ll make it.

For her part, though, she frames her ambitions more modestly.

“I don’t feel I want to go back to Portugal right away,” she says. “There’s a better quality of life there, but I have so many things yet to learn, I want to stay here a while.”