Mary Ellen Desmond is a Philadelphia treasure: a chanteuse whose musical moods swing from dark to light, a musician capable of great sensitivity and nuance, a teacher who responds to the needs of every student. That includes local singer/songwriter Matt McAndrew. He was a contestant on this season of NBC's

The Voice

and studied voice with Desmond in his freshman and sophomore years at the University of the Arts. All this, and Desmond still makes her annual Comfort & Joy concert for HIV/AIDs-related charities a must during the Christmas season.

Desmond is a recording veteran, primarily in jazz, with several post-bop and standards vocal albums. And her voice has matured since her stage start in the 1980s.

"With jazz, I think my stylization of lyrics and melody has gotten more creative, my phrasing has become more interesting and flexible," Desmond says. "When I listen to early recordings of myself and compare them to how I feel I sound today, I don't think I'm as cautious in my delivery of a lyric and a melody now. I try not to let technique overshadow emotion." With every song, Desmond looks to tell a personal story with deeply etched emotion. Her Comfort & Joy Holiday Jazz band, now celebrating its 11th year with her (Larry McKenna, tenor sax; Tom Lawton on piano; Lee Smith on bass; and Dan Monaghan on drums), powers the storytelling.

Among the beneficiaries of this annual concert are the Church of St. Luke & the Epiphany's Hospitality Center (which offers meeting space to Act Up, Action AIDS, and Philadelphia Fight); and the Fikelela AIDS Project, which fights to reduce new HIV infections and works with abandoned and orphaned children affected by AIDS/HIV.

"This year, after discussions at St. Luke's, it was agreed that Fikelela is still a very deserving recipient of concert proceeds," Desmond says. "The Hospitality Center is undergoing changes in how it serves the local community. The good news is that it's experiencing less of a demand, in part due to the advancement in medications to treat infected persons, and survival rates have improved. That's not to say that there should be less attention given to the disease." About 35 million people, including 3 million children, are infected worldwide.

Desmond and crew offer not just jazzed-up Christmas music fare, but also songs appropriate to winter, happy or sad, like McKenna and Melissa Gilstrap's new original ballad, "Perhaps This Wintertime."

"The holidays are not a great time for everyone, and if I can offer a song or two for someone to connect to and gain some comfort from so they don't feel alone or isolated, someone that might be having a difficult time, that's important to me," Desmond says. "There are reasons the concert's titled Comfort & Joy, you know. And it's always good to - and I risk being corny here - give to a charitable cause during the holidays. It feels great."

Mary Ellen Desmond's Comfort & Joy Holiday Jazz Benefit Concert plays at 6 p.m. Sunday at the Church of St. Luke & the Epiphany, 330 S. 13th St. Tickets: $20 general admission, $10 students & seniors. Information: 215-732-1918, www.slatechurch.org.