The Crossing, the sterling Philadelphia-based chamber choir, continue their exploration of social and environmental issues with ‘Motion Studies’, a vibrant pairing of Justine Chen’s Shallow Breath and Stealth and Nicholas Cline’s watersheds. Both scores pose the kind of virtuosic challenges these singers savour while commenting on topics as complex as they are intriguing and worrying.

Chen’s work distils texts from the Jena Osman poem that gives the disc its title. The impacts of data and machines on human life are reflected in impish, earnest and ominous choral activity. Chen uses silences with subtle power, often stopping the motion in its tracks, and her spare musical imagery portrays everything from earthly ecstasy to anxieties perpetrated by forces seemingly beyond containment.

The code-like motifs ‘dit dit dit’ and ‘dah dit dah’ are woven into the 13 sections amid evocative techniques, including breathy passages, growls, whispers, rubbings, recited texts and sudden exclamations. As always, the singers of The Crossing, led by Donald Nally, are precise and nimble, able to sustain long lines, clarify layers of dense counterpoint and pinpoint the expressive intent of every detail, however minute or cataclysmic.

Their skills are also ideal for Cline’s nine-movement study of the importance of water and its effects on the world and humankind. The opening wordless prelude, the work’s longest movement, is entrusted to a solo tenor saxophone (played with remarkable control and tonal nuance by PRISM Quartet’s Matthew Levy), which later interacts with the choir.

Among the eminent figures whose texts provide illumination are John Muir and Henry David Thoreau, and an excerpt from the Supreme Court’s Winters Doctrine bewails the fate of Native American water rights. Cline’s sonic vocabulary ranges from darting phrases to rich choral webs and ethereal passages. Sounds of bubbling water and rain help bring the narratives into striking, sometimes unnerving focus.