Wesla Whitfield, who overcame partial paralysis to become a preeminent vocal stylist, winning acclaim for her interpretations of the Great American Songbook and acquiring a devoted following that included many celebrated singers, died Feb. 9 at her home in St. Helena, Calif. She was 70.

The cause was complications from bladder cancer, said her husband and longtime pianist, Mike Greensill.

Ms. Whitfield sang in the chorus of the San Francisco Opera before turning to the music of Irving Berlin, George and Ira Gershwin, Cole Porter, Richard Rodgers, Lorenz Hart and other classic songwriters from the first half of the 20th century.

She recorded more than 20 albums and appeared at the White House and New York’s Carnegie Hall, yet she seemed most comfortable in smaller settings better suited to her intimate style of musical storytelling.

“In a music world that sometimes seems overrun with out-of-tune cabaret crooners, would-be jazz singers and commercially driven imitators,” Chicago Tribune jazz critic Howard Reich wrote in 2005, “Whitfield emerges as the real thing, a vocalist who has something distinct and personal to say with virtually every tune she addresses.”

Ms. Whitfield had a reedlike, instantly recognizable voice and sang with precise diction, perfect pitch and almost no vibrato. She became known for an unadorned yet emotionally powerful vocal style that illuminated every changing mood of a song’s lyrics.

She was sometimes called a jazz singer, sometimes a cabaret performer, but she resisted efforts to classify her approach to music.

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“I’m not a jazz singer,” she told the San Francisco Chronicle in 1995, “and I don’t consider myself a cabaret singer. I don’t claim to be anything. I just show up at the gig.”

Just as adamantly, Ms. Whitfield refused to be limited by her disability, which left her in a wheelchair after she was shot in 1977 by would-be robbers during an attempted holdup.

“It’s got nothing to do with my music,” she told the Boston Globe in 1998. “The thing I’ve come to realize — you can write this down — is that life is unfair. No matter how good I get as a singer, it is always going to be qualified by my disability, and that’s what’s unfair. So my way of railing against it, very gently, is not to make an issue of it.”

Yet many listeners, including her husband, believed that Ms. Whitfield’s private ordeal brought a more concentrated dramatic focus to her singing.

“I think being in the wheelchair actually defined her artistry,” Greensill said in an interview. “It forced her to sit there and sing the song.”

Ms. Whitfield drew most often on music from the 1920s, ’30s and ’40s — the era of the so-called Great American Songbook — but did not consider the songs nostalgic. Their eternal themes of love, desire and heartache, she said, remain true in any age.

With most songs, Ms. Whitfield performed the often-overlooked introductory verse, which she used as springboard into the more familiar melody. She and Greensill often subtly reshaped songs by changing time signatures or slowing down traditionally up-tempo tunes, such as “Tea for Two,” revealing fresh dimensions in the lyrics.

She could evoke romantic longing, rejection and confusion all at once with a simple line such as “Hey, you, give me a clue” from Jimmy McHugh and Harold Adamson’s “I Just Found Out About Love.” In Rodgers and Hart’s “Glad to Be Unhappy,” for instance, she added a wry twist of irony to the line “Fools rush in, so here I am.”

“You have to realize that I’m up there doing my own personal therapy every night,” she told O, the Oprah magazine, in 2005. “I’m doing that for myself but also for everybody in the audience, because we all feel that way.”

Weslia Marie Edwards was born Sept. 15, 1947, in Santa Maria, Calif. Her father was an oil field welder, her mother a bookkeeper and homemaker. (Her name was pronounced “Wesla,” despite its original spelling. In 1998, Ms. Whitfield dropped the “i” from her stage name.)

She sang and played piano in childhood and studied music and drama in college, graduating from San Francisco State University in 1972. She then joined the San Francisco Opera chorus, singing behind such stars as Joan Sutherland and Beverly Sills.

“I’d sneak off after a performance to sing in piano bars,” she told the Chronicle. “In opera, the voice was the only thing of importance. The lyric and the story didn’t count, and that was boring to me. I’m very interested in the song and the story that it has to tell.”

In April 1977, she was accosted on a San Francisco street by two boys who appeared to be no older than 12. She was shot in the back and paralyzed from the waist down. Her assailants were never caught.

During her recovery, Ms. Whitfield later admitted, she attempted suicide, but counseling and physical rehabilitation led to a renewed dedication to music. She worked as a paralegal and computer programmer while singing at night and slowly emerging as a featured attraction in San Francisco.

Her first two marriages, to Richard Whitfield and Wilfred Berg, ended in divorce.

In 1981, she began working with Greensill, a British-born jazz pianist who had settled in San Francisco. They married in 1986. Greensill wrote virtually all of his wife’s musical arrangements.

“Wesla taught me the importance of storytelling in the lyrics, and I think I taught her to be looser and swing,” Greensill told the Chronicle in 2011. “That was the real marriage of our styles.”

In addition to her husband, survivors include a sister.

Ms. Whitfield released her first recording in 1987 and quickly became a favorite of other singers, including Tony Bennett, Bobby Short, Margaret Whiting and Michael Feinstein. When she appeared in 1995 at a star-studded Frank Sinatra tribute concert at Carnegie Hall, her version of Berlin’s “How Deep Is the Ocean?” drew a standing ovation. She had monthlong residences at New York’s Algonquin Hotel, appeared at the White House in 1996, sang with symphony orchestras, and appeared on national television and radio broadcasts.

Before her performances, Ms. Whitfield was carried onstage by her husband, who placed her on a stool next to the piano. In recent years, she performed from her wheelchair, but she never mentioned her disability from the stage.

“I haven’t been through any more than most other people,” she told People magazine in 1996. “What happened to me was just more dramatic. Yes, it ages you; yes, it molds you; yes, it mooshes your brain around. That’s what life does — if you’re lucky.”