Frank Sinatra transformed popular music. Often cited as the single finest interpreter of American standards, he influenced generations of vocalists such as Nat King Cole and Carmen McRae by focusing on phrasing and matching narrative nuance and emotional naturalism with amazing breathing control. In the 1930s, Sinatra starting bringing back "old" songs by such masters as Cole Porter while he was still a Big Band singer. He became a national institution in the '40s, and even though Ray Charles has praised the flawless technique of this Columbia period, Sinatra kept evolving. Starting in the '50s he concentrated on groundbreaking concept albums and a fresh Big Band sound with master arranger Nelson Riddle. Sinatra explored every nuance of emotion on these Capitol and Reprise albums and influenced the work of Ella Fitzgerald and Peggy Lee. Beginning in the '70s, when rock ruled, his voice and output became erratic but some brilliant work remains. Though Sinatra always viewed himself as a popular singer, jazz musicians hold his work in the highest esteem. Miles Davis and Lester Young often interpreted standards through his versions and avant-gardist John Zorn has said that in his own way, Frank Sinatra was as much a jazz improviser as Charlie Parker.