Ana has a stuning Contralto voice, singing mainly in the chest register. In her music, she has performed with a range of G#2 to G5, breaking into head voice usually between Bb4 to C#5, though she has performed D5 in the chest/belt register.
Her warm, dark timbre, coupled with the full sound in the lower range, makes her stand out in the popular music world.
The video I have chosen to highlight her voice is the duet she performed with another Brazilian singer, Seu Jorge, live in concert: a version of Damien Rice's The Blower's Daughter, which, in Brazilian, is called É Isso Aí.