In Gyorgy Ligeti’s Chamber Concerto, the 13 required players — even though they constitute an ensemble — are treated as soloists. And there are occasions when the score calls for the 13 to head off in different directions. They introduce different themes, if fractured phrases can be called that. Their rhythms are different, as are their speeds. They begin and stop at different moments. The effect at those moments is of listening to something splintered.

And yet, what one hears seems also to fit, to come together, to be a structured unit, to be a composition. How that happens is a mystery. So is how 13 musicians can be so focused as to carry out their individual assignments while surrounded by all those conflicting sounds. And so, too, is how someone can make sure it all happens.

Well, the someone who made it all happen on Tuesday night in Indiana University’s Auer Hall was David Dzubay. And the 13 musicians who successfully paid attention to conductor Dzubay while keeping their focus were members of the New Music Ensemble.

As a result, what the audience heard and watched (the watch every bit as engrossing) was a riveting performance of Ligeti’s 1970 concerto, a multi-layered, drifting, shifting work that, when performed as properly as it was, can still arouse rapt attention, even admiration.

Dzubay placed the Ligeti first in a program that challenged his musicians throughout. He relinquished his front-and-center spot for a while, however, to Elliott Bark, an IU Jacobs School of Music doctoral candidate, studying both composition and conducting. As conductor, Bark was mighty good guiding eight musicians through “Some Assembly Required,” a set of 10 short items written in 2010 by guest composer Sydney Hodkinson, until his retirement in 1999 a long-time faculty member at the distinguished Eastman School of Music.

For this listener, Hodkinson’s aural exercises proved the most interesting and descriptive of Tuesday’s fare. For the opening piece, which he called “Frenzy,” Hodkinson composed just that: frenzied music. For the last, “Rush hour,” there was hurry. “Dawn trek” was quiet and misty. “Toy box” was quixotic, playful; “Midnight moves,” menacing; “Whirligig,” like machinery out of control; “Spectral shadows,” ghostly, and so forth. The material was imaginative and the instrumentation clever. Bark and the musicians treated “Some Assembly Required” as if no more assembly was required in the performance. It was excellent.

Tuesday’s concert ended with Bruno Maderna’s 1972 “Giardino Religioso” (“Religious Gardens”), the title paying tribute to Paul Fromm, whose foundation commissioned the work. “Fromm” is the German for the Italian “Religioso.” Twenty musicians gathered for the Maderna, with Dzubay again as conductor. The strings (six violinists, two violists, one cellist and one double bassist) inhabited the balcony space in front of and to the sides of the organ. On stage were pairs of musicians on horns, trumpets, percussion, harps and pianos.

They produced super-quiet phrases and developments up front and at the end. They produced a super-loud climax in the middle. Along the way, one heard passages chorally unified and those in planned absolute disarray. Everything appeared to be as required, including the double bass solo that finishes “Giardino Religioso,” a haunting exposition beautifully played by Greg Vartian-Foss.