Montserrat Caballé. Erich Auerbach/Getty Images hide caption

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Montserrat Caballé: A Voice Of Passionate Grandeur

Caballé could be imposing at full voice, but she showed her real greatness when singing intimately.

Working with the most basic human utterances, Monk's vocal music sounds fundamental and timeless. Massimo Agus/Courtesy of Universal hide caption

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Meredith Monk: A Voice For All Time

Simple and unadorned, Monk's vocal music sounds as if it has always meant to exist.

Rooted in local African rhythms, mbalax music has allowed Youssou N'Dour's voice to soar with a whole new freedom. Matt Cardy/Getty Images hide caption

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Youssou N'Dour: The Voice Of Senegal

The Senegalese singer is a musical chameleon capable of a seductive whisper or a siren's cry.

George Jones Hulton Archive/Getty Images hide caption

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George Jones: The Voice Of Heartbreak

George Jones, who died Friday at 81, could pull and bend notes until they made listeners hurt.

Luther Vandross' legendary voice has been called "flawless" and "as smooth as silk." Scott Harrison/Getty Images hide caption

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Luther Vandross: The Velvet Voice

The late soul singer's legendary voice has been called "flawless" and "as smooth as silk."