Watch the Ortner-Roberts Duo play a few of their songs and talk about their music. (Video by Ricardo Robinson)

Inside a small house on a back alley in the Mexican War Streets, a clarinet and piano move together from a classic Hungarian tune to a 1930s Benny Goodman standard to an Argentinean tango.

A Victrola sits in the corner next to the Baldwin upright piano. Photographs of famous musicians and posters from jazz events line the walls of the close living room.

The music carries so much energy and weight that the air thickens and the colors in the room dim — all that exists is the clarinet and piano.

The music stops and the players fill the sudden quiet with light-hearted bickering.

The Ortner-Roberts Duo do not hope for anything more than lifting peoples’ spirits through their music.

Susanne Ortner-Roberts, a German-born clarinetist, and Tom Roberts, a Pittsburgh native and pianist, strive to share their love of music and the joy it brings them with each note they play.

“The nicest compliment we get after a show is, ‘Oh, that made us so happy,’” Susanne says in her light German accent.

With a musical selection enveloping swing, calypso, Harlem stride piano, early jazz, klezmer, gypsy, tango, rembetika and valse musette, the duo’s tagline “Hot World Chamber Music” is a perfect fit.

To Pittsburghers, the Ortner-Roberts Duo may be a group that appears in places like Schenley Plaza or the Allegheny Library, but to the international music scene the Ortner-Roberts are well-known and respected masters of their instruments.

Susanne also plays with the German quartet Sing Your Soul, and offers klezmer — a type of traditional Jewish music — workshops in Germany and the United States. A German journalist is writing a book about her that should come out in Germany this year.

Tom composed music for Martin Scorsese’s “The Aviator,” has appeared on The Tonight Show with Johnny Carson and is recognized as one of the top Harlem stride pianists in the world today.

Together they travel to Germany three times a year to perform and teach, and frequently play throughout the eastern United States, including New York City.

But that doesn’t mean they take those small, local gigs begrudgingly — they want to expose their music to as many listeners as possible.

 “We play everywhere where people will have us,” Tom says — they even do house parties.

Passionate music of all genres, mostly from the 1910s to the 1940s, inspires them.

Tom Roberts and Susanne Ortner are internationally acclaimed musicians who love making people happy. (Photo/Ricardo Robinson)

“To me almost every piece of music is beautiful if it’s played with passion,” Susanne says. “Of course we bring all our passion to [our music].”

Tom’s criterion for a good song is one that’s not only played masterfully, but moves him physically, emotionally, intellectually and spiritually. “You’ve got to be able to shake your tuckus to it.”

Many nights the couple will pull a record from Tom’s “intense record collection,” which dominates one kitchen wall, and listen to it on the Victrola until they truly understand the piece. If they want to incorporate it into their repertoire, they transcribe it note for note.

“You may think it’s going to sound horrible,” Tom says as he puts a record from the 1920s on the Victrola, “but this is as close as you can get to being in the room [with the musicians]. It even has volume control.”

As the first notes emerge from the antique machine, he turns the volume up, then down. Although not crisp and clean like a CD, the music sounds more authentic, more human.

“There’s a lot of listening, and then you can take the essence,” Tom says, shutting off the Victrola.

In spite of working with many ethnic styles of music that are often politicized, the two shy away from that frame of mind.

“You do want to be authentic,” and understand it, Tom says, but “it’s simply music, there doesn’t need to be a big agenda.”

Rarely do they take a piece as is. Once they transcribe the music, they add their own flair or combine it with another piece, sometimes using themes from classical music to tie the two together.

“We love classical music and we always come back to it,” Susanne says.

The idea for their musical “gumbo” came early in their relationship. They met in 2006 when Susanne was a visiting musician at the University of Pittsburgh and both were hired for a performance.

“I was hired to perform at a gig, and there Tom was.” Susanne flashes him a smile.

They wanted a reason to continue playing together, but since she mainly played klezmer at the time and he mainly played jazz, they juxtaposed the two styles.

After Susanne returned to Germany, they met again in Verona, Italy and toured together. “Everywhere we went that trip, people were asking if we were married or telling us to get married,” Tom says.

In 2008 the Ortner-Roberts Duo released their first album, “A Trip to America,” on their own Wild About Harry records, named after their dog.

“A Trip to America” blended Yiddish and creole music. Once the couple pulls together enough capital, they plan to record a new album with a wider range of styles that will reflect their constantly changing and evolving library.

“There’s so many passionate songs from all over the world,” Susanne says.

With the whole world to choose from, Tom settled on the Northside, and Susanne joined him.

Although he grew up in Pittsburgh, he moved away and had no desire to come back until he recorded some music in the now-closed Audiomation studio on North Avenue and thought, “Oh my god, this is so great, this is so beautiful, there’s every imaginable type of person here.

“The longer you live here, you love it more and more.”

Susanne likes to call it the “Island of Misfit Toys,” because the Northside is filled with authentic people who do their own thing.

“I really don’t like the whole mall mentality,” she says. “I like unique things and that is what I like the most.”

Their enjoyment of the unique and diverse certainly shines through in their music, as does their affection for each other. Few musicians play together with as much chemistry and grace as the Ortner-Roberts Duo, although it’s sometimes difficult to tell from the way they constantly tease each other.

“We’re definitely married,” Tom says with a laugh.

For more information, visit the Ortner-Roberts Duo on the web at www.myspace.com/ortnerrobertsduo. Their next performance is March 20 at 7:30 p.m. at Allegheny Unitarian Universalist Church on North Avenue, and on March 13 they will play on SLB Radio at 11:05 a.m.