Nonesuch will release a/rhythmia, the new album from Alarm Will Sound, the 20-member group described by the New York Times as “one of the most vital and original ensembles on the American music scene," on September 15; it is available to pre-order now in the Nonesuch Store.

Though known for its focus on contemporary music, on a/rhythmia Alarm Will Sound performs 14 pieces from composers spanning six centuries, united by a common purpose. Each was inspired by and/or was attempting to explore the concept of "arrhythmia": “want of rhythm or regularity, specifically of the pulse.” The resulting work, on the ensemble’s fifth album and its first complete album on Nonesuch, upends order and expectation, often taking ideas akin to minimalism and refracting them through a fun-house mirror.

Central to the disc is the player piano work by Conlon Nancarrow, who has intrigued composers like György Ligeti, also represented by a piece here, as are short pieces from English composer-filmmaker Benedict Mason’s Animals and the Origins of Dance and longer works by such artists as Michael Gordon, electronic-music duo Autechre, and the 15th-century composer Josquin des Prez.

After the group performed several of these pieces in a Carnegie Hall program last year, the New York Times declared that “Alarm Will Sound shows an admirable commitment and a spirit of adventure.” New York magazine, in its Year in Culture survey, cited the concert as one of the Top Ten Classical Events of 2008.