The cause was complications from a stroke two years ago, said her stepdaughter, Sandra de Novellis.
Ms. Sloane was among the last singers who came up in the big-band tradition of jazz and swing music and was seen as an heir to the jazz vocal tradition of Ella Fitzgerald, Sarah Vaughan and her idol, Carmen McRae.
In the 1950s and early 1960s, she headlined at nightclubs; shared the stage with jazz musicians such as Coleman Hawkins, Ben Webster and Clark Terry; had a major-label recording contract; and sometimes substituted for Annie Ross in the hip vocal trio Lambert, Hendricks and Ross.
During a 1961 appearance at a jazz festival in Newport, R.I., Ms. Sloane discovered that her pianist did not know the introductory verse to Richard Rodgers and Lorenz Hart’s “Little Girl Blue.” As she sang the verse a cappella, a hush fell over the crowd, and critics were mesmerized by her confidence and vocal control. She was heralded as a rising star in jazz.
“She is one of the very few singers who can make conversation stop in a club,” jazz critic Nat Hentoff once wrote. “She has presence … She gets inside you — the knowing voice, the sensuous textures, and the lyrics that become a conversation.”
She released two albums on Columbia, sang several times on the “Tonight Show,” became a regular on Arthur Godfrey’s national radio program and was featured at nightclubs from the Village Vanguard in New York to the Hungry I in San Francisco. She appeared on the same bill as comedians Woody Allen, Lenny Bruce and the Smothers Brothers, and, for a time, her opening act was Richard Pryor.
Ms. Sloane once introduced herself to Duke Ellington, saying she made it a point to sing at least one of his tunes in every performance. She went on to make three albums of Ellington’s music and recorded his song “I Didn’t Know About You” no fewer than four times. She befriended the sometimes acerbic McRae, who was a disciple of Billie Holiday and became Ms. Sloane’s mentor in interpreting a song.
“Singers have the responsibility to make you feel moved in some way when you hear us sing,” Ms. Sloane told the Los Angeles Times in 1993. “You should feel pain, if there’s pain in the song, or happiness or joy or whatever there is. And the singer should let you hear that they know something of this experience we’re singing about and convey it with sincerity.”
She sometimes lamented that she was born a generation too late. Closer in age to John Lennon and Janis Joplin than to Fitzgerald or Holiday, Ms. Sloane saw her once-promising career collapse in the mid-1960s with the rise of rock-and-roll.
Her manager, who doubled as the road manager for the Beatles and Rolling Stones on their first U.S. tours in the 1960s, invited Ms. Sloane to meet the new British musicians. She was sitting in the dugout at Shea Stadium in New York in 1965 when the Beatles performed before 55,000 screaming fans.
“I got nauseous,” she later told music writer Marc Myers in an interview for his JazzWax blog. “The kids had been drifting away from jazz for years. But by this concert in 1965, they were completely gone, and I knew they were never coming back. You could see it. You could hear it.”
Columbia dropped Ms. Sloane from its roster, and by the end of the decade, she had all but given up on singing. From 1969 to 1977, Ms. Sloane lived near Raleigh, N.C., where she worked as a legal secretary and sang occasionally in a local nightclub. She moved back to New York to restart her career with the help of her boyfriend at the time, pianist Jimmy Rowles. Ms. Sloane made a few small-label recordings, but her understated approach was out of step with the era of disco music and jazz-rock fusion.
Ms. Sloane split up with Rowles — “He was an alcoholic, and it was impossible to change him,” she said — survived a suicide attempt, and moved back to North Carolina, planning to manage a jazz club in Chapel Hill. She worked as a part-time DJ on WUNC, a public radio station, but the jazz club folded, and by 1985, she found herself almost destitute.
“My phone was cut off,” Ms. Sloane told the New Yorker magazine in 1987. “The bank took my car. I knew the electricity would be next, and I had no idea how I would pay my rent … I picked up the phone and, miraculously, the dial tone came on, and before they cut it off again, I started calling clubs where I had worked. I had forgotten that if you don’t do things for yourself, no one will do them for you.”
In 1989, with a more stable home life, she released her first album in years, “Love You Madly.” Critics noted that her husky, honeyed voice was stronger than ever, her musical sense of swing was impeccable, and the troubles she had endured only brought greater depth to her interpretations of such songs as the rueful lament about heartbreak, “I Could Have Told You So,” by James Van Heusen, with lyrics by Carl Sigman:
He’ll find someone new to have fun with
Ms. Sloane went on to record more than a dozen late-career albums, often with such acclaimed musicians as saxophonists Benny Golson and Phil Woods and pianists Kenny Barron and Bill Charlap. Jazz players considered her their musical equal, yet even when she was singing at breakneck tempos, she enunciated every word with perfect clarity.
“The magic rests in her warm, swinging delivery,” Myers wrote in the liner notes to Ms. Sloane’s 2009 album, “We’ll Meet Again.” “With a breathy vibrato, Carol’s voice smolders with tenderness and seduction, like Lester Young’s horn. Her approach is so intimate and confessional that you’re often left feeling as though you’ve just been told a lover’s secret.”
Carol Anne Morvan, the daughter of textile factory workers, was born in Providence on March 5, 1937, and grew up in Smithfield, R.I. She sang in church choirs, then at 14 began singing as Carol Vann with a local big band, making $9 a night. She never learned to read musical notation.
At 18, she married a Providence disc jockey, Charlie Jefferds. They were divorced in 1958, the same year Ms. Sloane joined a band led by Les and Larry Elgart. When the two brothers parted ways, Ms. Sloane went on tour with Larry Elgart’s band for two years and legally changed her name to Carol Sloane.
In 1986, she married entertainment executive Buck Spurr, and they settled in Stoneham. He died in 2014. In addition to de Novellis, of Harrison, N.Y., survivors include a stepson, David Spurr of Wilmington, Mass.; and five grandchildren.
Ms. Sloane’s final album, “Live at Birdland,” was released in 2022, 60 years after her debut recording, “Out of the Blue.” A documentary about her life is scheduled to premiere next month.
In her later years, Ms. Sloane occasionally led master classes at the New England Conservatory, where she had strict rules for her students.
“The young women hated me because I wouldn’t let them scat-sing,” she told the New York City Jazz Record. “You have to pick one of these Duke Ellington ballads, I told them, and sing it for me as I wish it to be sung … I thought it was interesting that they all showed some resistance. To them, jazz singing meant scat and improvisation, but to me, it means conveying the lyric, because that’s what Carmen taught me. She said tell the story, feel the tug in the heart.”