Baltimore-based pedal steel guitarist Susan Alcorn has taken her instrument well beyond its expected idiomatic confines to develop one of the most distinctive voices in improvised music. On Pedernal, she leads a quintet made up entirely of strings, save for drummer Ryan Sawyer. Accompanied by violinist Mark Feldman, guitarist Mary Halvorson, and bassist Michael Formanek, she weaves an unusual ensemble fabric with her dark and warm pedal steel tone at the center. This unique instrument allows her to create lyrical legato through lines even in highly abstract contexts, as well as surpassingly strange harmonies and sonic textures—all with an approach to phrasing and articulation that is identifiably pedal steel through and through. The players take up challenging written passages with poise and dig into the varied improvised scenarios that Alcorn cooks up. The elements all coalesce with particular clarity on “Circular Ruins.” On the final track, “Northeast Rising Sun,” the mood of cloudy mystery lifts: The band can be heard laughing as they rehearse a section with handclaps, then jump into an infectious melody that wouldn’t be out of character for Pat Metheny.