Argentina’s Mercedes Sosa, who began her professional career in 1965, remains one of the world’s most widely recognized and best-loved voices of the folk-rooted Latin American genre known as nueva canción, and the progressive social critique and commitment to equality and human rights the music embodies. Corazón Libre (“free [spirited] heart”) takes Sosa back to her acoustic origins, the sound and sentiment that have inspired three generations at home and abroad to sustain hope under the brutal shadow of U.S.-backed military dictatorships that prevailed over much of the region from the 1960s through the 1980s. This is Sosa at her finest, her soulful, dramatic voice against the unadorned backing of acoustic guitar, strings, hand percussion and vocal harmony. Building on the Argentine milonga, chacarera, huayno, zamba, chamamé and tonada, she sings of street children, abandonment, suffering in love and out, the power of song to illuminate and inspire. Particular treats include a revival of her anthem “Todo cambia” (“everything changes”), and the distinctive line drawings of Sosa by her long-time friend and companion in song, Joan Baez.