“To me, the duo is the ideal,” says Jon Abbey, co-curator of the Erst-Quake annual festival of improvised music. “There’s no place to hide. You’re more out front than in a group, but you can’t just relax and do your own thing.”

Of the 20 performances at this year’s four-day installment, which begins on Thursday at Tonic on the Lower East Side, all but two will be by duos. The lineup boasts an internationally diverse array of sound-makers, from Korean-American electronic duo English, which performs on Friday, to Japanese voice-and-sinewave pair Cosmos on Saturday, to Norway’s Jazkamer, which recently released an album of heavy-metal dirges, on Sunday. “There’s a really wide range of aesthetics coming together,” Mr. Abbey said.”The hope is that it will all add up to more than the sum of its parts.”

Mr. Abbey began ErstQuake two years ago with drummer Tim Barnes. They named the festival after their respective record labels, Erstwhile and Quakebasket, which release the same kind of thoughtful, open-ended music their festival showcases.

ErstQuake performances are often more like conversations than concerts, with emphases on careful listening and real-time response. As these musicians see it, each drum strike, electronic noise, or horn tone presents an opportunity, a new sonic doorway to step through.

Before ErstQuake began in 2004, Mr. Abbey was already curating his own international series, AMPLIFY. “The idea was to take what I was doing with AMPLIFY and root it in the New York community,” Mr. Abbey said. “[Arizonan percussionist] Jeph Jerman brought a night of duos and trios to New York in 2004, and I thought, ‘Wow, we can do something like this here.’ So it’s nice to have Jeph as part of ErstQuake this year, because he inspired it initially.”

Mr. Abbey was also inspired by a festival organized by Japanese improviser Otomo Yoshihide in Austria in 1999. “The musicians there would tell me, ‘We’re going to play in a certain way because of what’s following us,'” Mr. Abbey said. “It made me see how individual sets can interact with the whole festival and hopefully form something greater.”

This year, Mr. Abbey has expanded ErstQuake’s palate with help from a third co-curator, Chris Wolf of the label Little Enjoyer. As a result, veteran musicians like 66-year-old Austrian trombonist Radu Malfatti on Saturday and 73-year old minimalist Phill Niblock on Sunday will grace the same stage as 20-something noiseniks Michael Bernstein of Double Leopards and Aaron Dilloway, formerly of Wolf Eyes, both playing Friday.

“I love that range,” Mr. Abbey said. “I love that Saturday night will start with the near-silence of Malfatti and [Basque provocateur] Mattin, and end with Dilloway, who’s going to play some crazy metal and then just go nuts,” Mr. Abbey said. “But then Mattin’s set with Tim Barnes on Friday night will be just about as loud as music gets. Each of the nights is designed to go generally from soft to loud, although nothing is written in stone. Even as one of the curators, I’m sometimes quite surprised, which I think is fantastic.”

One of the weekend’s most interesting pairings should be Sunday’s firsttime collaboration between Mr. Niblock and Jason Lescalleet, both of whom work with loops recorded by other musicians. “I think Phil might be making decisions in real time, which he almost never does,” Mr. Abbey said.

Also of interest will be the performance by Mr. Jerman, who uses natural tools — sticks, rocks, debris — to make his small, careful sounds. Mr. Jerman will play with Greg Davis on Thursday, and Mr. Barnes and drummer Sean Meehan on Sunday. Many ErstQuake participants will also appear multiple times in different lineups. “These musicians are all are such quick problem solvers,” Mr. Abbey said. “The idea is to push them, to give them a whole new set of problems.”

Ultimately, Mr. Abbey hopes to host performances that have a lasting effect on the audience. “The music creates its own internal language in each set, and sometimes that’s hard to pick up quickly,” Mr. Abbey said. “Not to say there isn’t a visceral impact, because there certainly is. But it takes a while to process the details. It’s like reading something in a foreign language.”

September 28 through October 1 at Tonic (107 Norfolk St., between Rivington and Delancey streets, 212-358-7501).