Mason Bates

Mason Bates performing at the 2012 Mercury Soul event. (May 9, 2013)

The players lift their bows with the customary this-is-the-end flourish, finishing a movement of a Shostakovich string quartet, and the audience claps. A few "Whoo!" yells escape from the back of the room. Some people whistle.

As the quartet launches into the next movement, a member of the audience stands up and says to his companion, "I'm going to get another beer. You want anything?"

Classical music, especially the subgenre of recently composed works usually called new music, has gotten out of the concert halls and band shells to hit bars, clubs and other venues where drinks are served during the performance and audience protocol doesn't demand docile silence.

A central example of this phenomenon is Mercury Soul, the half-classical, half-dance-music event taking place Friday, masterminded by Chicago Symphony Orchestra composer-in-residence Mason Bates.

"It's an entire experience," Bates said. "I shy away from the word 'concert.' It's more of a show or even a party."

If things go according to plan, Mercury Soul attendees will walk into the North Side rock venue Metro and see a dramatically lighted space. DJ sets will allow the crowd to dance and mingle, and live instrumentalists might be improvising with the DJ. Then, later in the evening, a small orchestra will play along with the techno, as program notes for the music are projected on the wall. Then the chamber orchestra will play a piece in its entirety, before providing musical accompaniment for a transition back to the DJ.

Bates wrote the intros and "outtros" for the orchestra, which consists of CSO players, and he will spin during the dance-music portions of the event as his alter ego, DJ Masonic. Collapsing his two worlds means getting some thumping into the classical listener's auditory diet, but also bringing some precision to the usually free-form techno world.

"It's more surgical (than just spinning records), like being on a SWAT team where you jump out of a van and spin 28 minutes of tech house and then you have to get out at the end point," Bates said.

Even concerts that present only traditional classical music have gone bar-hopping, as with the (Un)familiar Music Series, presented at the West Side bar and adventurous music venue the Empty Bottle. Doyle Armbrust, also a violist with the string quartet Spektral Quartet, books the series, which has its fifth-season installment May 22 with Ensemble Dal Niente.

(Un)familiar grew out of a recurring project Spektral has played at the Bottle called Sampler Pack, in which the ensemble intersperses movements of classical-repertoire string quartets by composers such as Mozart, Haydn and Bartok with contemporary works. August 2012's Sampler Pack served as an inaugural for (Un)familiar.

"It was born out of something we were doing with Spektral, (wanting to) expand beyond the typical concert hall, which keeps some amount of distance in between the audience and the performers," Armbrust said.

The Bottle almost forces crowd interaction, architecturally. "That's something you get at the Bottle in the way you set up," Armbrust said. "The musicians are not up on stage — they're down on the floor."

To date, (Un)familiar has hosted the string quartets Chicago Q and Spektral, the wind quintet City of Tomorrow and a new-music hootenanny called (Re)New Amsterdam.

Dal Niente's May 22 concert features guitarist Jesse Langen and soprano Amanda DeBoer Bartlett in a program consisting entirely of world premieres consistent with the ensemble's often-astringent music choices.

"We tend to present programming that has difficult content, without apology," said Ryan Muncy, Dal Niente's executive director. "Here's what we found the last few years: Audiences really like that difficult content. They like to be challenged intellectually. Audiences don't like that decorum, that protocol that goes along with listening in a formal concert hall."

Classical musicians agree that what's keeping a subsection of music lovers away from their performances isn't the concerts — it's the concert hall.

"The perceived veneer of classical music is something that as reasonably young musicians, we are kind of appalled at," Armbrust said. "It's not a level of pretense that we are ever a part of."

Clapping anxiety and the social pressure of dress keep away people accustomed to wearing jeans to work and responding instinctively. If the conventions of the Lyric Opera and the CSO apply even at concerts with $15 tickets, then less-wealthy, more-casual listeners see all classical music as anniversary-night, special-occasion material.

"It's nice to dress up, go out to dinner and do something that has an air of sophistication to it," Armbrust said. "Those opportunities are there. But especially with new music, none of us feel that these are museum pieces that have to be listened to reverentially with hands clasped."

In contrast, patrons at bars or rock venues don't worry that their fellow audience members might judge them.