On Infra, the second album of work by French composer Pascale Criton (b. 1954), microtonal tunings and the techniques congenial to them are employed to create sound environments of incremental variations on pitch and color. The pieces collected on Infra and performed by the Ensemble Dedalus are for solo cello (Deborah Walker), cello and violin (Walker and Silvia Tarozzi), and a chamber quintet of cello, violin, guitar, flute and trombone (Walker, Tarozzi, Didier Aschour, Amélie Berson and Thierry Madiot, respectively). The sound gets its particular flavor from the tunings used; for the string instruments, Criton specifies a tuning of 1/16 tone, an interval chosen for its near imperceptibility. The focus of the compositions thus falls on eliciting shadings of sound color and the microdissonances and other aural effects produced by closely ordered pitches; there’s a certain understated drama in the discrepancies between slightly differentiated tones whose defining gaps widen and narrow within a restricted audio space. The performances are technically accomplished and highly effective in conveying the subtle movement and finely calibrated hues of Criton’s soundworld.