With the fifth installment of Soundspace on Sunday, we should go ahead and call the Blanton Museum’s series what it is: the most successful new music event in the city.

With last year’s Austin Critics’ Table Award for “MusiCircus,” the combination of music and art has vaulted the twice-annual Soundspace series into must-see status, by being ambitious and affordable.

“It’s top-notch performers; world class talent for nine dollars,” says Soundspace’s organizer Steve Parker. And University of Texas students get in for free.

Last fall, the fourth Soundspace concert drew about 700 people to the Blanton, and the museum’s manager of public programs, Adam Bennett, in an email, called it “one of our most successful programs.”

So what are people coming to see?

In a word, the unexpected. Last fall, it was 80 trombones playing the airy atrium.

For the John Cage tribute in 2011 it was a clarinetist playing inside an elevator.

The key to navigating the unpredictability? You have the total freedom to move, anywhere throughout the museum. Post-modern opera not your fancy? Head to the contemporary galleries to see a percussionist and a modern dancer, or a jazz combo’s brass section blasting music above Richard Long’s sculptured stone circle.

“The concerts are supposed to be intuitive,” Parker says. “You should be able to follow your instincts.” So, no lengthy program notes.

What’s on tap for this Soundspace?

There’s Austin composers Graham Reynolds and Peter Stopschinski, saxophone quartet Bel Cuore and Convergence, a new vocal ensemble featuring members of Conspirare, singing music by Philip Glass and some vocal improvisation.

And how about alt orchestral band Mother Falcon, some opera and a “Bohemian Rhapsody” sing-a-long? (“Awakening your inner Garth,” from the movie “Wayne’s World,” Parker kids.) “What I really want is for Bel Cuore to play the guitar solo,” he adds, grinning.

Parker, who teaches trombone at UT-San Antonio, has thought a lot about the audience — specifically, the kind of audience that has almost no relationship with art or any music besides pop.

This thinking comes from an arts outreach program he did in Camden, N.J., which he calls “probably the most dangerous neighborhood” he’s lived in. And he’s joined another program, in Philadelphia’s Chinatown North, a section of Chinatown that was cut off by a highway.

Bringing art music to the masses is tough. The culture barrier can be fierce.

“It makes you question ‘What value does this piece (of music) serve, and why am I doing it?’” he says. “When you’re coming from institutions, you’re around like-minded people, and you stop asking those questions.”

The Blanton audiences have responded to the answers.

It’s an entry point, says Parker. Hearing 80 trombones playing drone sounds, “depending on the situation, could’ve been an unpleasant experience.” But the simple fact of not being tied to a chair in a darkened auditorium frees the listener.

And as the audience has grown, Parker says, Soundspace has grown too — “aesthetically and in scope.”

The series also has made it clear that when it comes to classical music, Austin has a deep bench.

Most of the performers in the upcoming event haven’t played in the series before. One of them is Julie Fiore, the director of One Ounce Opera. Her group’s goal, she says, is to “reimagine opera in unexpected places.” Parker summed up their Soundspace plans by saying the group was performing “lots of crazy stuff.”

“We had all these ideas that kept circling,” Fiore says, about their tour of the museum. True to the series, she’s keeping them under her hat, but revealing that one piece involves opera and a live DJ, and in another, the audience will apparently be “playing the singers.”

Now that is keeping Austin weird.