DiFranco strikes a responsive chord

Ani DiFranco debuted a song titled ''Nov. 4, 2008'' in Sunday's concert.

Something often overlooked in the journalist-driven mythologies of Ani DiFranco (paragon of indie-minded business success, charged symbol of conflicted gender politicking) is what a dynamic guitar player she is. Those in attendance at Symphony Hall on Sunday night were quickly reminded of this as DiFranco transformed from busker to poet to rock star and back, sometimes all within the span of a single song.

On the crowd-pleasing "Little Plastic Castle," DiFranco worked up a percussive acoustic rhythm, strumming out rapid bursts of punchy chords as thousand of diehards hung on her every word. It was hard to say who seemed more excited by the results: DiFranco basking in the glow of the rapturous welcome or the capacity crowd standing throughout the performance, laughing at her stories, and screaming out declarations of love. Standing up, DiFranco said of the stately hall, "is probably not what this room was designed for."

What it is designed for is maximum acoustic efficiency. The three other members of the band (on drums, upright bass, and percussion) worked the angles of the room with light cymbal brushes, chunky bass notes, and reverberating vibraphone chimes that created an organic, enveloping warmth. Here the band built a funky jazz rhythm, there they offered only minimalist embellishments. On the new song "Nov. 4, 2008," DiFranco beamed with delight as she sang: "The victory was ours. Never had so many people donated to a campaign." It was presumably about Barack Obama, although it was hard to make out the rest of the lyrics over the roar of the crowd. At the very least, the thundering applause settled any question about the political affiliation of an audience at an indie folk-rock concert in Boston.

Less exciting was DiFranco's jazz-club slam-poet persona, with its by now dreadfully cliched exhalation meter, or the reliance on corny sexual innuendo she often employs (to the audience's delight). She hit her stride on the rocking numbers, wringing the neck of her acoustic as if coaxing some imaginary feedback from it, finger plucking rapid-fire melodies, and bouncing about the stage in rhythmic glee. Better still were the moments of defiant optimism, such as on the title track of her latest album, "Red Letter Year," where her plangent voice unwound from anguished whisper to rabble-rousing indignation.

Kindred spirit Erin McKeown opened with a set of forcefully projected, emotive folk. On the songs "Put the Fun Back in Funeral" and "Born to Hum," she directed the audience to accompany her on whispers and three-part harmony humming. The fact that we all played along should give an idea of the performance's intimacy and winning charm.