Sarah Jarosz Tests the Mainstream

In modern Nashville, songwriting is often a matter of professionalized co-writing: planned, mix-and-match collaborations by appointment, musicians sharing a room to come up with sturdy material.

It’s a method that Sarah Jarosz had largely shied away from until she made her seventh studio album, “Polaroid Lovers.” The LP, arriving Friday, includes songs she wrote with behind-the-scenes Nashville stalwarts including Jon Randall, Natalie Hemby and the album’s producer, Daniel Tashian, who worked on the country-psychedelia fusion of Kacey Musgraves’s “Golden Hour.”

On “Polaroid Lovers,” Jarosz reaches toward a broader audience while still maintaining her individuality. The songs are more plugged in, muscular and reverberant than her past albums, which were intimate and largely acoustic. But her particular perspective — at once clearheaded, thoughtful, vulnerable and open to desire — comes through.

The first song Jarosz wrote with Tashian was “Take the High Road,” with a chiming chorus that declares, “It won’t be the easy way/Saying what you want to say.” In a video interview from her home in Nashville, with string instruments hanging on the wall behind her, Jarosz said that the song’s lyrics “are almost a thesis for the whole album. You know, ‘I’m tired of being quiet — time to face up to the fear.’”

Jarosz, 32, is a luminary in acoustic Americana, where bluegrass, folk, jazz and chamber music mingle with pop and rock. Born in Austin, Texas, and raised in Wimberley, a small town nearby, Jarosz emerged as a teenage bluegrass prodigy, playing mandolin, guitar, banjo and the instrument she considers her “soul mate”: the octave mandolin, pitched an octave below the standard mandolin, which she often uses for solos or countermelodies. The instrument sounds a little darker and twangier than acoustic guitar in the same range — a hand-played lower voice that answers Jarosz’s own hovering mezzo-soprano.

She made her first four albums in Nashville, and she was urged to write songs with more seasoned musicians; she chose not to release any of them. “The quote-unquote ‘Nashville co-writing’ thing had been pushed on me when I was like 18, 17, making my first record,” she said. “I was really closed off to it back in that time, because I felt like I was still finding my voice. And I was worried that if I went into those co-writing rooms prematurely, that I would get lost at sea.”