“This isn’t the place to come see polished, finished pieces.”

 Petr Kotík said that proudly on Saturday night at the wrap party for New Opera Days Ostrava, a four-night foray into the outer reaches of modern music. NODO is an outgrowth of Ostrava Days, a biennial gathering of composers, players, students and devotees of contemporary music that Kotik founded in 2001. Akin to its famous predecessor in Darmstadt, Ostrava Days offers two weeks of intensive workshops capped by nine days of performances that have a particularly powerful resonance in a hard-edged industrial city near the Czech-Polish border.

 Opera became part of the mix when Jiří Nekvasil, a stage director and intendant of the National Moravian-Silesian Theatre in Ostrava, offered his facilities for performances in the festival’s off-years. The first NODO took place in 2012, opening with John Cage’s Europera 5, directed by Cage’s assistant Andrew Culver and featuring Martha Herr, the Brazilian soprano who sang the première of the piece in 1979. Even Kotík was surprised by the reception it got.

“The hall was full and the audience was so attentive you could hear a pin drop,” he says. “At the end, people stood up and cheered. It was astonishing.”

This year’s festival also opened with a finished professional piece, a co-production with the Schwetzinger SWR Festspiele titled Re:igen by Bernhard Lang, a regular at Ostrava Days. But the emphasis was on new and experimental pieces, some still works in progress. The results were uncommonly bold, wildly uneven and thoroughly entertaining.

The runaway hit of the other four pieces (three world premieres, one European premiere) was The List of Infinity, a “spoken opera” composed by Martin Smolka and directed by Jiří Adámek. The former is a well-known Czech composer whose work is marked by imagination and humor, and the latter a rising Czech stage director whose new form of “sonic theatre” has won awards at a number of theatre festivals. Taking a cue from Umberto Eco and his book The Infinity of Lists, they used four singers and a shifting soundscape to present a running string of lists, from simple ABCs to the names of angels, in settings ranging from psychedelic to starkly symbolic.

The recitation, some spoken, some whispered, some pitched in a musical key, started with rapid-fire precision and took on a dazzling variety of contours and intonations over the 70-minute performance. Coupled with Smolka’s music, which began in a neo-classical vein and then ran the gamut from minimalist atmospherics to industrial clanging, the effect was mesmerizing. Countertenor Jan Mikušek appeared midway through, a cryptic character in a white tuxedo who added crystalline high notes and dark dramatic undercurrents – the X factor in an ultimately unknowable universe. Infinity seemed almost palpable as his final cry faded into the cosmic vortex created by a brilliant synthesis of music, text and staging.

Kotík’s Master-Pieces offered a less successful example of how to handle large blocks of text – in this case, a lecture on the nature of art by Gertrude Stein. Soprano Kamala Sankaram did an heroic job segueing back and forth from spoken word to demanding vocals, and a trio of male singers offered welcome counterpoint. But a philosophical monologue proved hard to bring to life – at a discussion afterward, director David Rau talked about struggling to find “where the theatrical energy could come from in the text.” Kotík’s penetrating score of mostly solo violin played by the eloquent Pauline Kim Harris provided a somber atmosphere, musically engrossing in its evocation of the joys and pain of the artistic process.

The rigor of artistic creation was the subtext of No No Miya, a reworking of the eponymous Noh play by expat Czech composer Rudolf Komorous, who fled to Canada after the Prague Spring reform movement was crushed in 1968. Written in 1988 and premiered in Vancouver, No No Miya had never been performed in Europe. Komorous’ mix of avant-garde angst with traditional elements of Noh drama mirrored the blend of Eastern and Western musical elements in his score, with neither being entirely successful. But director Jiří Nekvasil put a jolt in the production by upending the normal performer-audience relationship, putting the audience onstage and the performers in the seats. It was a clever bit of stagecraft that proved to be more radical than the piece itself, a slow-moving work weighed down by another overabundance of text.

Eager to have a young voice in the mix, Kotík and festival Executive Director Renáta Spisarová commissioned the finale from Mojiao Wang, a 32-year old Chinese composer who was a student at last year’s Ostrava Days. After many delays – unable to find a librettist, Wang finally asked her father to take on the task – she arrived in Ostrava with Encounter, a patchy take on a by-now familiar story about a couple that breaks apart and then reconnects through social media. Director Xinxin Tang had all of three days to work on the staging, which was more like a recital, with the singers performing mostly from music stands. But Korean soprano Hyun Yi Kim showed a wonderful voice, and the score, another mix of Eastern and Western elements, featured plenty of musical tumult and rambunctious percussion that kept the piece lively and entertaining.

For all the inventiveness onstage, the primary strength of the festival was the same one that undergirds Ostrava Days – Ostravská Banda, an international ensemble Kotík put together specifically to play modern music. The group does superb work with seemingly impossible pieces at Ostrava Days, and at the opera festival provided razor-sharp, expert playing in the pit for all the performances. It was a heady reminder that hearing modern music played properly can be an exhilarating experience.

And part of the festival’s remarkable accomplishment: After four nights of living on the edge, polished, finished pieces will never seem as interesting again.