Settling nicely into her skin

Gillian Welch is no screamer, yelper or blues shouter. Her voice is wistful and weary, singing of spiritual quests and first loves, lonesome thoughts and leaving home. So there was a quiet ease to her performance Wednesday at the Coach House in San Juan Capistrano, but also a strong will that emerged from the emotional content of her songs.

Her specialty is acoustic folk and bluegrass, the same strain of old-timey music that has been a key resource for rockers Bob Dylan and Neil Young over the decades. Welch’s approach is almost obsessively traditional, which can still be heard on her upcoming fourth album, “Soul Journey.” But she’s not oblivious to modern pop techniques and attitudes, which were called on for the needs of the moment.

Welch abandoned her prepared set list, joking about the lack of witty comments between songs. “We really don’t know how to leave you in a good mood,” she said. “We figured that’s not why you came.” Standing beside her was longtime collaborator David Rawlings, whose guitar picking was crucial, bringing a rock ‘n’ roll edge to some of the instrumental passages and adding layers of melody and fire. Their dual guitars were understated and subtly forceful. Rawlings was also called on to sing “Big Rock Candy Mountain,” a feisty bluegrass tune.

Welch’s career enjoyed a significant boost with her role in the hit soundtrack for “O Brother, Where Art Thou?,” which revealed a large audience for the traditional music the major labels had ignored. The success of that album, which included appearances by Ralph Stanley, Emmylou Harris and Alison Krauss, was a surprise even to those involved.

At the time of her 1996 debut, Welch was dismissed by some critics for adopting an Appalachian sound and persona that were not hers to claim. The Los Angeles-raised singer-songwriter had not come down from the mountain any more than John Fogerty was born on the bayou. But this many years later, Welch is a key player in a growing community that has genuinely embraced the sound as its own.