The cause was cardiac arrest, his wife, Jeanie Scott, said.
Mr. Scott’s career finished on a high note, with steady work from the early 1990s on, as well as a Grammy nomination, glowing reviews and praise from well-known fellow performers like Madonna, who called him “the only singer who makes me cry.” But the first four decades of his career were checkered, with long periods of inactivity and more lows than highs.
After enjoying sporadic success in the 1950s, he had almost none in the 1960s. Albums he recorded for major labels in 1962 and 1969, which might have jump-started his career, were quickly withdrawn from the market when another company claimed to have him under contract. He virtually stopped performing in the 1970s and made no records between 1975 and 1990.
The fact that both men and women considered themselves Mr. Scott’s disciples is not surprising: because of a rare genetic condition called Kallmann syndrome, which caused his body to stop maturing before he reached puberty, Mr. Scott’s voice never changed, and he remained an eerie, androgynous alto his whole life.
Standing 4-foot-11, with a hairless face to match his boyish voice, he was originally billed as Little Jimmy Scott, and he was presented to audiences as a child until well into his 20s. In his mid-30s he unexpectedly grew eight inches taller and, although he otherwise remained physically unchanged, doctors told him an operation might stimulate his hormonal development. He decided against it.
“I was afraid of entering uncharted territory,” Mr. Scott told David Ritz, the author of “Faith in Time: The Life of Jimmy Scott” (2002). “Besides, fooling with my hormones might mean changing my voice. Whatever the problems that came with the deficiency, my voice was the one thing I could count on.”
Mr. Scott’s condition left him incapable of reproduction.
James Victor Scott was born on July 17, 1925, in Cleveland. The third of 10 children, he lived in orphanages and foster homes after his mother was killed in a car accident when he was 13. After singing in local nightclubs for a few years, he went on the road in 1945 with a vaudeville-style show headed by Estella Young, a dancer and contortionist. He moved to New York City in 1947 and joined Lionel Hampton’s band a year later.
His 1950 recording of “Everybody’s Somebody’s Fool” with Hampton set the pattern for his later work. A mournful ballad of love gone wrong, the song was delivered with feverish intensity and idiosyncratic, behind-the-beat phrasing. The record was a hit, but because it was credited on the label simply to “Lionel Hampton, vocal with orchestra,” few people knew that Mr. Scott was the singer.