Jazz vocalists are, by and large, not an adventurous lot. Most prefer to stick to standards and re-interpretations of contemporary pop songs. While this is a totally valid form of musical expression, I rarely seek out recordings made by vocalists when I want to hear risky, modern, cutting-edge music. With her second recording, "Mobile," the Portugese vocalist Sara Serpa boldly grabs this stereotype by the scruff of the neck and shows it out the door. "Mobile" is a startlingly individualistic collection of beautifully developed and arranged original compositions for voice and a four-piece ensemble. Serpa's clearly not afraid of words – each piece is inspired by books she's read over an 18-month period preceding this recording. Yet, on "Mobile," she functions largely as an instrumentalist, singing wordlessly. What I really like about Serpa's approach is that – contrary to the jazz tradition of scat singing – she does not try to mimic a saxophone or trumpet. Sure, she has a great sense of jazz phrasing, but what you hear is her voice. And what a voice it is! Clear, unaffected, and vibrato-less, with a crystalline purity that seems both fragile and diamond-hard.