The title of Aros' Train Song immediately calls to mind a locomotive's duple rhythm (chugga-chugga, chugga-chugga), which makes it somewhat ironic that a straight-up duple or triple rhythm is nearly impossible to find on the album. Aros, an Amsterdam-based sextet co-led by saxophonist Rob Armus and pianist Marion von Tilzer, can occasionally drop an infectious beat, as evidenced by Armus' astringent but danceable "Tango." Most of the time, however, they choose complex metrical juxtapositions-a winsome 12/8 melody against mercurial 11/8 accompaniment on Von Tilzer's "Song of the Heart," Armus multiplying interlocked rhythms in 5 and 6 to make a trudging song titled "30"-that have some drive but speak more to the head than to the feet.
Armus and Von Tilzer draw mostly cool sonorities from Aros' combination of trumpet, sax, violin, bass, cello and piano, putting the music at a bit of a remove. Armus, who comes from a jazz background, frequently fills time with Philip Glass-style arpeggios that prove no match for the occasional improvisational outburst, particularly when Armus or trumpeter John Korsrud are improvising. Von Tilzer's classical background has apparently inspired a more wholehearted embrace of groove; she composed the album's best track, "Ostinato," which takes off from a modest piano figure, gradually piles on timbral and harmonic layers and evolves into something forceful and vast.
Still, many of the other tracks on Train Song seem to be stuck halfway between a cerebral and a physical approach, sticking hard to their complex rhythms and never really showing exuberance. I wish Aros would occasionally lay aside the formal innovations and, like their album's namesake, simply barrel forward.