It’s hard to think of another artist quite like Yo La Tengo, who have been tending their own garden with a low-key determination for 33-odd years, a part of but also apart from the constantly morphing musical landscape around them. Formed by singer/guitarist/recovering music critic Ira Kaplan and drummer/singer Georgia Hubley in a loosely Velvet Underground format in 1984, the group has weathered every alt-rock trend since then: Making their debut in 1985 — with a song on Coyote Records’ Hoboken-themed “Luxury Condos Coming to Your Neighborhood Soon” compilation, if memory serves — the group rose through the burgeoning Ameri-indie scene of the ‘80s, had some alt-rock radio hits and were distributed by major labels during the alt-rock explosion of the ‘90s, then took on more experimental elements with 2000’s “And Then Nothing Turned Itself Inside Out” and have continued to evolve from that model in the years since. Along the way they’ve collaborated with dozens of other musicians — ranging from the Kinks’ Ray Davies to Texas savant Daniel Johnston — and undertaken multiple auxiliary projects, the longest-running of which is their beloved, semi-annual week of covers-and-guest-appearance-heavy Hannukah concerts. Through it all, they’ve remained both open and impervious to outside influences, evolving but always sounding distinctly and resolutely like themselves. You could almost do a mock-time-lapse video of the past 30 years of alternative music with Ira, Georgia and bassist James McNew — the new guy, who’s only been with the group for 26 years — in the center, slowly taking on new elements as the scenery around them warps dramatically.

All of which makes it no surprise that the group’s 15th full album and first in five years, “There’s a Riot Going On,” is one of their most challenging to date. In deliberate contrast to its title — a nod to both Sly and the Family Stone’s galvanizing 1971 album of the same name as well as the explosive social climate in which both that album and this one were spawned — the music is very, very chill, almost ambient at times, with wafting textures, gentle percussion and hushed vocals on nearly all of the tracks; a special concert in Brooklyn premiering the album last month found the three members behind keyboards or playing percussion for much of the set. Even though Yo La Tengo can get plenty loud when they want to — Kaplan can wreak gloriously ear-splitting feedback from his guitar, but only does so for a brief, muted moment on this album — it’s as if the group were taking today’s explosive social environment and internalizing a calm, almost meditative reaction/response to it. There’s some pep early in the tracklist — particularly on the percolating “She May, She Might” and the atmospheric power-pop of “For You Too,” a new classic in the group’s voluminous catalog — but the overall vibe is dreamy hush, murmurs and whispers, with occasional interludes like the brief and slightly goofy instrumental “Esportes Casual,” which could be the soundtrack for a 1960s lifestyle commercial.

“There’s a Riot Going On” probably won’t jump-start any riots and reveals its beauty gradually, but it’s a welcome addition to the group’s vast oeuvre that finds them evolving into yet another new shape. Hopefully we won’t have to wait another five years for the next.