As she does before any concert, Julie Leven practices.

And practices some more.

"I have to be heard at my best, all the time," she said. "It’s so personal. When I play my violin — that’s me"

She is, as you may have guessed, a professional violinist, performing with the Handel and Haydn Society at Symphony Hall, spending every Fourth of July on stage at the Hatch Shell with the Boston Pops.

But this night she is performing as part of a string quartet at the Shattuck Shelter in Jamaica Plain. Her approach is informal. She talks directly to the audience scattered across a room with concrete walls and a green tile floor. Here she responds to a man who asks if she’s playing first violin.

A partial wall separates the bunks that on this night — like every other — will fill up with people seeking food, warmth, a roof over their heads. They’re here for the basics. So why give them Beethoven?

"Classical music is one of humankind’s greatest artistic creations and it wasn’t created to be exclusive," Leven said. "It was created for composers to tell stories about being human, about emotions and just making sense of the world. Why not classical music in the homeless shelter? Because perhaps someone who doesn’t even have a home needs it even more."

Leven was inspired to bring classical music to homeless shelters after reading about a similar project in New York City. From a laptop in her Arlington home, she now runs Shelter Music Boston . It’s a big job.

She coordinates seventy concerts a year at local shelters, creates a new program each month and is always raising money, because — although the concerts are free — the musicians are paid.

"I imagined when I started this organization that we would be proving that classical music can create change and in order to do that we would commit to it in a professional way," Leven said.

The musicians prepare for shelter concerts the way they would for any other performance. But this experience is unique. There are constant interruptions, such as this one when the night’s bed lottery is announced over a loudspeaker.

"All the Shelter Music Boston musicians have said, 'Wow, after playing these concerts I don’t get so ruffled when I play Symphony Hall or at Jordan Hall because there’s a funny noise or something fall down,'" Leven said. "It’s so minimal compares to what goes on in the shelter."

The music creates a welcome calm.

"As Julie starts to play, the shelter becomes much quieter, people settle in," said Elizabeth Condron, who manages volunteer outreach at the Shattuck.

Leven says playing here is as rewarding as any other concert venue in the world, in part because the audience offers immediate feedback.

"We have people saying, 'My shoulder hurt when I sat down and the pain went away during the concert,'" Leven said.

"We get a lot of comments about, 'The music made me feel hopeful,'" she said. "One of my favorites was a woman at the Shattuck Shelter, in fact, who said, 'The water was music for my soul when it was thirsty.'"

Those reactions bolster Leven’s belief that classical music transcends the status quo, whether you hear it at Symphony Hall or the Shattuck Shelter.

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