On her fourth solo album "Undercurrent," Sarah Jarosz doubles down on understated elegance.

Not that anything she's ever done could be described as rowdy. But in her first release since graduating from the New England Conservatory of Music, Jarosz strips the music down across the board to two or three instruments per song behind her usual shimmering vocals. The effect is a subdued song cycle that slows down your metabolism - the kind of music to turn to after a frustrating day at work, say, or as an antidote to feeling frantic.

There has always been acoustic elegance to Jarosz's work, which might be why she sometimes fares better with critics than record buyers. She's a musician's musician, and here she draws support for her own serene playing - on guitar, octave mandolin and banjo - from Guster's Luke Reynolds, Parker Millsap and Nickel Creek co-founder Sara Watkins.

The songs themselves, all written or co-written by Jarosz, reflect the album's title, as they are understated and evocative. If there's a danger it's that they are so unobtrusive that they become wispy, but several cuts seem likely to find permanent playlist homes. "Back of My Mind," in particular, co-written with Joey Ryan of the Milk Carton Kids, combines sublime, bluegrass-influenced harmony with a sweetly wistful sentiment to brilliant effect.

It's all first-rate songwriting, the kind that doesn't so much bring the house down as inspire murmurs of approval from the coffee house crowd. That's something an emerging talent like Jarosz has been hearing for quite some time, but it deserves a larger audience.